Re: Work Around or Fix of Waves XO Found?
One of the downsides to FIR filters is ringing, what this means is that the roll-off eventually slows and the FIR filter begins to oscillate through the passband.
The workaround was to use higher roll off rates and also use the Low Ripple method for the FIR filters. This give you -100dB rejection in the passband. Accurate is around -60dB and Normal is -80dB.
Every FIR filter exibits this problem as much in the same way the an IIR filter distorts phase but its definitely inaudible when your talking about the low ripple method and steepish slopes.
Interestingly, Algoritmix's Orange PEQ is a linear phase filter but doesn't exhibit the ringing artifact because it works in the time domain. Downsides of its use are big latency and lack of very steep slopes, infact 4th order is the max rolloff you can use with this one.
For me the Waves package works best so far and I really wouldn't worry about the 'artifact' I discussed a few pages back when I was a little less wise. Its a non issue.
kfr01 said:
One of the downsides to FIR filters is ringing, what this means is that the roll-off eventually slows and the FIR filter begins to oscillate through the passband.
The workaround was to use higher roll off rates and also use the Low Ripple method for the FIR filters. This give you -100dB rejection in the passband. Accurate is around -60dB and Normal is -80dB.
Every FIR filter exibits this problem as much in the same way the an IIR filter distorts phase but its definitely inaudible when your talking about the low ripple method and steepish slopes.
Interestingly, Algoritmix's Orange PEQ is a linear phase filter but doesn't exhibit the ringing artifact because it works in the time domain. Downsides of its use are big latency and lack of very steep slopes, infact 4th order is the max rolloff you can use with this one.
For me the Waves package works best so far and I really wouldn't worry about the 'artifact' I discussed a few pages back when I was a little less wise. Its a non issue.
Still trying to pick a card - I have a couple of X-Fi cards in the house now but still looking at audiophile cards.
The SB X-Fi card isn't bad though, does anyone know if two of them can be clocked together?
The Delta 1010Lt card looks good, and the later posts mention the ESI card - an ESI WaveTerminal 192M (4 in 8 Out) looks good too - if I can get 2 of them in a single machine. I haven't seen if these take external clocks though.
The SB X-Fi card isn't bad though, does anyone know if two of them can be clocked together?
The Delta 1010Lt card looks good, and the later posts mention the ESI card - an ESI WaveTerminal 192M (4 in 8 Out) looks good too - if I can get 2 of them in a single machine. I haven't seen if these take external clocks though.
Zodiac said:
I prefer the IR1-L as not only is the interface cleaner (the extra features of IR-1 simply aren't used) it also seems slightly quicker when like for like features are enabled.
At first I thought this was due to the internal precision being lesser on the L version but reading through the waves manual actually pointed out that the two operate on exactly the same engine.
I personally prefer Voxengo Prisine Space but IR1 is fine also.
Two more options I haven't seen listed here:
Reaktor 5:
I haven't played with this, but the description of its low-level graphical DSP programming capabilities looks tantalizing:
"REAKTOR Core Technology breaks new grounds with regard to flexibility and power, allowing the creation of new types of instruments. The REAKTOR Core Technology, new in REAKTOR 5, has been over three years in the making and opens up a whole world of innovative sound generators, effects and more. A completely new layer of functionality that is seamlessly integrated into the REAKTOR architecture, Core Technology now enables true low-level signal processing design, and allows for an unlimited range of custom modules including oscillators, filters, EQs, delays and more. "
For the Mac only:
Logic Pro, which includes IIR & FIR filters and Space Designer, an excellent multi-channel convolution plug-in. One of the great advantages of using the Mac is the native multichannel 24/96 support. Mac OS X audio support walks all over MS' at this point (this should change with Vista).
Reaktor 5:
I haven't played with this, but the description of its low-level graphical DSP programming capabilities looks tantalizing:
"REAKTOR Core Technology breaks new grounds with regard to flexibility and power, allowing the creation of new types of instruments. The REAKTOR Core Technology, new in REAKTOR 5, has been over three years in the making and opens up a whole world of innovative sound generators, effects and more. A completely new layer of functionality that is seamlessly integrated into the REAKTOR architecture, Core Technology now enables true low-level signal processing design, and allows for an unlimited range of custom modules including oscillators, filters, EQs, delays and more. "
For the Mac only:
Logic Pro, which includes IIR & FIR filters and Space Designer, an excellent multi-channel convolution plug-in. One of the great advantages of using the Mac is the native multichannel 24/96 support. Mac OS X audio support walks all over MS' at this point (this should change with Vista).
Anyone have any thoughts on the best way to pass 6 or 8 channels of audio digitally from a PC to a Mac? I'd like to use a PC as a front-end and a dedicated Mac as the audio processor. The only solution I've seen so far is the Lynx AES-16, but I'd need one in each machine (and maybe 2 in the Mac, depending on the # of output channels). This is ridiculously expensive. There must be a better way. Maybe over firewire? But I haven't found a transmitter driver for the PC + a receiver driver for the Mac.
Thanks in advance for your thoughts.
Brad
Thanks in advance for your thoughts.
Brad
Here's another potential low-cost, PC-based room correction system:
http://www.etfacoustic.com/software/RPlusD/RPlusDIntro.PDF
It looks like it's still under development, but has the potential to rival the Audyssey + DEQX. AFAIK, Audyssey only does room correction based on 17 measurements and doesn't offer crossover emulation, and DEQX, while it does crossovers, only takes measurements from a single point. I haven't used R+D, yet, so I can't speak to the quality or ease of use, but I've been using ETF for the past 3 years and it's an excellent program. So, I have high hopes for R+D.
http://www.etfacoustic.com/software/RPlusD/RPlusDIntro.PDF
It looks like it's still under development, but has the potential to rival the Audyssey + DEQX. AFAIK, Audyssey only does room correction based on 17 measurements and doesn't offer crossover emulation, and DEQX, while it does crossovers, only takes measurements from a single point. I haven't used R+D, yet, so I can't speak to the quality or ease of use, but I've been using ETF for the past 3 years and it's an excellent program. So, I have high hopes for R+D.
Hi All:
I've been banging my head for months how to do DRC XO, etc on a PC and I run into you guys! Wow, nice work.
You all seem to want to do DAC on your PC cards. I am convinced it's best to pass pure digital (either spidif or aes/ebu) both in and out from the pc. For me I don't even need DAC at all since I pass PCM 2 channel to each amp that does a PCM-PWM conversion and then output to the speaker drivers with variable gain based on volume settings. If you must have DAC down the chain you can do it external to the pc with whatever time base goodies and quality you want.
The audio amps are TI "purepath" chip implementations (Panasonic XR45, 55) and function as DACs with gain. I am unsing sanspeak woofers with Newform Reseach ribbon tweeters. These amps ("receivers") are a steal for what they do. You can control multiple amps with one remote to get n-channel volume control. You solve two big problems: volume control without hurting data stream or doing extra DAC conversions, multichannel volume control beyound the stupid limitations of the mainstream audio industry. On the XR55 when using stereo mode digital in you get 2x 100 watt amps per output channel for double the current.
To do the PC stuff I am looking to use a Lynx aes16src: (Windows 2000/XP: MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming and GSIF). This card lets you do 16 in and 16 out digital with 96khz 24bit or even 192khz. You can also hook up a Bigben clock to it if you want. I haven't tried it yet but if it supports all those drivers it should work with Console shouldn't it?
greensheen
I've been banging my head for months how to do DRC XO, etc on a PC and I run into you guys! Wow, nice work.
You all seem to want to do DAC on your PC cards. I am convinced it's best to pass pure digital (either spidif or aes/ebu) both in and out from the pc. For me I don't even need DAC at all since I pass PCM 2 channel to each amp that does a PCM-PWM conversion and then output to the speaker drivers with variable gain based on volume settings. If you must have DAC down the chain you can do it external to the pc with whatever time base goodies and quality you want.
The audio amps are TI "purepath" chip implementations (Panasonic XR45, 55) and function as DACs with gain. I am unsing sanspeak woofers with Newform Reseach ribbon tweeters. These amps ("receivers") are a steal for what they do. You can control multiple amps with one remote to get n-channel volume control. You solve two big problems: volume control without hurting data stream or doing extra DAC conversions, multichannel volume control beyound the stupid limitations of the mainstream audio industry. On the XR55 when using stereo mode digital in you get 2x 100 watt amps per output channel for double the current.
To do the PC stuff I am looking to use a Lynx aes16src: (Windows 2000/XP: MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming and GSIF). This card lets you do 16 in and 16 out digital with 96khz 24bit or even 192khz. You can also hook up a Bigben clock to it if you want. I haven't tried it yet but if it supports all those drivers it should work with Console shouldn't it?
greensheen
greensheen said:
Same here, Vil also does the same.
I'm using an RME HDSP9652 with an Apogee DA16X for clocking and DAC. I've got 3 ADATS with S/MUX giving me 12 channels capable of upto 24bit/96Khz. I really wanting to move over to AES though so I can use the Apogee DAC to the full with 24bit/192Khz.
At the moment though I'm completely redoing my entire PC setup for silent operation.
For those interested in a PCXO probably the most annoying aspect once its up and running is the noise.
Let's face it: You've got this wonderful setup that you've devoted hours and hours of work to with the result being fantastic audio. But whenever you play music you've got a constant whiring of fans in the background that simply wrecks any realism your system is capable of because the signal to noise ratio is destroyed thanks to the PC working in the background at 30-40dB. Its akin to but even worse than the parallel of amps causing the speakers to hiss or hum. No serious listener would ever but up with this.
I've tried previously to silence my PC's but the whole effort was pretty much in vain. Its a losing battle I thought and something you've just got to live with unless you're prepared to do crazy things like mix water with electronics as some of the real PC enthusiast do. For me that wasn't an option.
Its also been getting to me having two PC (even more noise!) in the listening room. Thanks to the power hungry nature of FIR filter and DRC on multichannel audio I've had to resort to a dedicated PC for audio processing. Hardly the worlds most elegant solution but it did ensure that everything was reliable and glitch free. Aside from the noise and inconvenience issue with two PC's you've also got the added expense of running and maintaining two machines. Many components are simply duplicated adding to the cost, one example is the use of two soundcards which can work out to be expensive depeding on the cards you choose not to mention a downright waste. So another real want of mine is a one box solution that can handle high definition playback and a 5.1 soundtrack with FIR filtering and DRC.
Can all this be achieved with todays technology?
To find out I've been chatting to some of the hardcore PC overclocking enthusiasts to see what products remove the most heat efficiently and conversely I've been talking to the HTPC crowd to find out what can be done quieten things down. After some hard saving I've finally got enough to amass a set of components for an ideal PC to suit these tasks. Last week I ordered the parts and here's the details:
Its an extremely heavy weight design and constitutes a largish outlay for my particular options but again I know of people that spend far more on a CD player or DVD player. So the value is relative and once again, in the eye of the beholder.
Everything has been carefully balanced between heat vs. noise. The noise control components are as follows:
Antec P180 'Silent' Case:
http://www.antec.com/uk/productDetails.php?ProdID=09180
Antec Phantom 500w PSU (fanless design):
http://www.antec.com/uk/productDetails.php?ProdID=05501
Scythe Ninja passive CPU Cooler:
http://www.quietpc.com/uk/amdcooling.php#ninja
120mm AcoustiFan Dustproof Fans (rated at less than 10dB on 5v):
http://www.quietpc.com/uk/casefans.php#acoustifandustproof
AcoustiPack Deluxe (v2) Acoustic Material Kit :
http://www.quietpc.com/uk/materials.php#apd
The Antec P180 case is the standout. Its built from a composite of 3 layer consisting of aluminium-plastic-aluminium. This has much better damping properties than simple alu or steel cases. This is evidenced by simply knocking on the side panel which yields minimal resonances unlike every other case I've ever had. The sound deadening properties of the case will be further enhanced with the addition of acoustic materials lining the interior. The P180 also offers an exeptionally well though out interior that allows for maximum cooling potential and inversely, maximum noise reduction. There's an excellent article discussing the case in detail here : http://www.silentpcreview.com/article249-page1.html
The Antec Phatom 500w is a passive PSU design so again no fans!
All these products just simply weren't available the last time I looked around a year or so ago, clearly the silent PC market is gaining momentum as the quality of design on all these products is quite exemplary.
The boring but necessary stuff is:
AMD Athlon X2 4400+ CPU (dual core) (passively cooled - no fans)
Asus A8N-SLI Premium Motherboard (passively cooled - no fans)
2Gb OCZ Platinum PC3200 CAS2.0 (2 x 1Gb config.)
Leadtek 7800GT Graphics Card
2 x 250Gb Samsung Spinpoint P120 Harddrives (RAID 0 config)
All pretty much standard fare but its worth noting that the motherboard is cooled with passively heatpipe technology - very smart and silent, it also supports SLI so I can move upto dual graphics card in the near future (I'm a gamer at heart).
The AMD X2 CPU features dual cores and is specialized for multitasking, I've got high hopes this will be able to run for example; Theatertek DVD along with Console in the background doing the audio processing at decent speeds.
2Gb memory sounds like more than enough but there's no such thing as too much when it comes to memory and space.
Lastly there's the Samsung harddisk which are widely regarded as the quietest available.
On the audio side of things:
Lynx TWO B soundcard with LS-AES expansion
Apogee DA16X (configured as master clock with 16 channel DAC)
I've actually changed a few things around. Before I was running two RME cards, one was a HDSP9632 in the dedicated audio PC and the other in the main PC was a HDSP9652. Instead I've sold both of these and moved on to the Lynx TWO B with the AES expansion board. Again the soundcard is connected up to the Apogee DA16X but this time I'm using AES instead of ADAT to transfer digital audio and I'm also clocking the Lynx via the Apogee using Wordclock256X or superclock as its sometimes known instead of just plain old wordclock.
This setup is a bit OTT and isn't particularly great value for money but it does offer a sound that's near perfect - is that worth the asking price? I'd say yes because the same performance isn't easily acheived for less but many would say that difference doesn't justify the cost. Eitherway there's many other ways to skin a cat, its just some are faster than others.
I'm in the process of building it all up but do have a couple of pictures to show:
The CPU cooler is a real monster thanks to it being passively cooled.
I've sound proofed the entire interior of the PC where possible and safe. Not shown is the case side panels which are also covered in acoustic damping material. This shot, however, is the backside of the motherboard tray:
Also inside the door:
And the final shot shows the unfinished state as of today:
I've got a few more components to add and then I can begin testing to see just how successful I've been. Remember my aim is a virtually silent PC and the ability to run HD video/games with full multichannel filtering and DRC audio processing all from one machine.
Let's face it: You've got this wonderful setup that you've devoted hours and hours of work to with the result being fantastic audio. But whenever you play music you've got a constant whiring of fans in the background that simply wrecks any realism your system is capable of because the signal to noise ratio is destroyed thanks to the PC working in the background at 30-40dB. Its akin to but even worse than the parallel of amps causing the speakers to hiss or hum. No serious listener would ever but up with this.
I've tried previously to silence my PC's but the whole effort was pretty much in vain. Its a losing battle I thought and something you've just got to live with unless you're prepared to do crazy things like mix water with electronics as some of the real PC enthusiast do. For me that wasn't an option.
Its also been getting to me having two PC (even more noise!) in the listening room. Thanks to the power hungry nature of FIR filter and DRC on multichannel audio I've had to resort to a dedicated PC for audio processing. Hardly the worlds most elegant solution but it did ensure that everything was reliable and glitch free. Aside from the noise and inconvenience issue with two PC's you've also got the added expense of running and maintaining two machines. Many components are simply duplicated adding to the cost, one example is the use of two soundcards which can work out to be expensive depeding on the cards you choose not to mention a downright waste. So another real want of mine is a one box solution that can handle high definition playback and a 5.1 soundtrack with FIR filtering and DRC.
Can all this be achieved with todays technology?
To find out I've been chatting to some of the hardcore PC overclocking enthusiasts to see what products remove the most heat efficiently and conversely I've been talking to the HTPC crowd to find out what can be done quieten things down. After some hard saving I've finally got enough to amass a set of components for an ideal PC to suit these tasks. Last week I ordered the parts and here's the details:
Its an extremely heavy weight design and constitutes a largish outlay for my particular options but again I know of people that spend far more on a CD player or DVD player. So the value is relative and once again, in the eye of the beholder.
Everything has been carefully balanced between heat vs. noise. The noise control components are as follows:
Antec P180 'Silent' Case:
http://www.antec.com/uk/productDetails.php?ProdID=09180
An externally hosted image should be here but it was not working when we last tested it.
Antec Phantom 500w PSU (fanless design):
http://www.antec.com/uk/productDetails.php?ProdID=05501
An externally hosted image should be here but it was not working when we last tested it.
Scythe Ninja passive CPU Cooler:
http://www.quietpc.com/uk/amdcooling.php#ninja
An externally hosted image should be here but it was not working when we last tested it.
120mm AcoustiFan Dustproof Fans (rated at less than 10dB on 5v):
http://www.quietpc.com/uk/casefans.php#acoustifandustproof
AcoustiPack Deluxe (v2) Acoustic Material Kit :
http://www.quietpc.com/uk/materials.php#apd
The Antec P180 case is the standout. Its built from a composite of 3 layer consisting of aluminium-plastic-aluminium. This has much better damping properties than simple alu or steel cases. This is evidenced by simply knocking on the side panel which yields minimal resonances unlike every other case I've ever had. The sound deadening properties of the case will be further enhanced with the addition of acoustic materials lining the interior. The P180 also offers an exeptionally well though out interior that allows for maximum cooling potential and inversely, maximum noise reduction. There's an excellent article discussing the case in detail here : http://www.silentpcreview.com/article249-page1.html
The Antec Phatom 500w is a passive PSU design so again no fans!
All these products just simply weren't available the last time I looked around a year or so ago, clearly the silent PC market is gaining momentum as the quality of design on all these products is quite exemplary.
The boring but necessary stuff is:
AMD Athlon X2 4400+ CPU (dual core) (passively cooled - no fans)
Asus A8N-SLI Premium Motherboard (passively cooled - no fans)
2Gb OCZ Platinum PC3200 CAS2.0 (2 x 1Gb config.)
Leadtek 7800GT Graphics Card
2 x 250Gb Samsung Spinpoint P120 Harddrives (RAID 0 config)
All pretty much standard fare but its worth noting that the motherboard is cooled with passively heatpipe technology - very smart and silent, it also supports SLI so I can move upto dual graphics card in the near future (I'm a gamer at heart).
The AMD X2 CPU features dual cores and is specialized for multitasking, I've got high hopes this will be able to run for example; Theatertek DVD along with Console in the background doing the audio processing at decent speeds.
2Gb memory sounds like more than enough but there's no such thing as too much when it comes to memory and space.
Lastly there's the Samsung harddisk which are widely regarded as the quietest available.
On the audio side of things:
Lynx TWO B soundcard with LS-AES expansion
An externally hosted image should be here but it was not working when we last tested it.
Apogee DA16X (configured as master clock with 16 channel DAC)
An externally hosted image should be here but it was not working when we last tested it.
I've actually changed a few things around. Before I was running two RME cards, one was a HDSP9632 in the dedicated audio PC and the other in the main PC was a HDSP9652. Instead I've sold both of these and moved on to the Lynx TWO B with the AES expansion board. Again the soundcard is connected up to the Apogee DA16X but this time I'm using AES instead of ADAT to transfer digital audio and I'm also clocking the Lynx via the Apogee using Wordclock256X or superclock as its sometimes known instead of just plain old wordclock.
This setup is a bit OTT and isn't particularly great value for money but it does offer a sound that's near perfect - is that worth the asking price? I'd say yes because the same performance isn't easily acheived for less but many would say that difference doesn't justify the cost. Eitherway there's many other ways to skin a cat, its just some are faster than others.
I'm in the process of building it all up but do have a couple of pictures to show:
The CPU cooler is a real monster thanks to it being passively cooled.
An externally hosted image should be here but it was not working when we last tested it.
I've sound proofed the entire interior of the PC where possible and safe. Not shown is the case side panels which are also covered in acoustic damping material. This shot, however, is the backside of the motherboard tray:
An externally hosted image should be here but it was not working when we last tested it.
Also inside the door:
An externally hosted image should be here but it was not working when we last tested it.
And the final shot shows the unfinished state as of today:
An externally hosted image should be here but it was not working when we last tested it.
I've got a few more components to add and then I can begin testing to see just how successful I've been. Remember my aim is a virtually silent PC and the ability to run HD video/games with full multichannel filtering and DRC audio processing all from one machine.
Hi, I have spent *many* years building a succession of quiet PCs and I agree it's VERY hard!!
The only machine which I owned which was really terrific was an Antec Sonata. I put in a fanless PSU (which runs pretty hot and I tried several because they all failed fairly quickly...). The other fan was a 120mm big boy on the back which spins really slow and was absolutely silent.
The Sonata was near inaudible in my room from very close and totally quiet from a distance. Also the cooling was incredible with temps at 30c or so with only the single 120mm fan at the back (compared with my Coolermaster boxes which have 7+ fans in them and the machine is much hotter!). Clearly design plays as much of a factor as number of fans!
The worst case I owned was the Claritas Strata fancy HTPC case. I have one for sale if UK buyer wants it. Lovely looking box, but zero silencing.
Also although most of the desktop style cases look best for HTPC the cooling is much, much worse than with a tower case. Also the tower case usually ends up on the floor, but the HTPC case ends up nearer ear height (and high freq whine is more audible in straight lines). So if looks aren't important then tower is the way to go
Antec seems to be a really solid choice if you just want something which works! I was very, very pleased with my Sonata case. I sold it and bought the Claritas case....
I am now using a "Heatsink Case" from HFX. It weighs a ton and has no fans as standard, just lots of heatpipes.
To be honest I think the "no fans" thing is a risk if you care about drives failing though. I added a small low speed fan just to get a small amount of air moving inside the case. Even a tiny fan will drop the temps 20-30C so it's worthwhile. Anyway, it's currently the best choice for me
OK, so now tell me: How have you found the Lynx compared with the RME 9652? Seems to me that they are going to be identical with the RME being 1/4 the price? Do you hear an difference bearing in mind you are spitting out digital?
How are you doing volume control with so many DACs? What would be perfect is if the Apogee had a master volume control (which didn't work in the digital domain)... I had to build a multiway attenuator using a DACT stepped switch - I have a remote control on it which allows me to change volume control from the couch. In practice I set it roughly to max volume that I need and control the volume using digital volume control in the player app - sure it looses some precision, but the RME 9632 DACs are around >110db so I hardly care if I loose a few bits at low volumes!
What kind of filters are you running now? I am using Brutefir at 44Khz with 65535 tap filters and it's tiny amounts of CPU compared with the amount needed for resampling. Brutefir does partitioned convolution and running at 2048 sample latency is ok, but dropping to 1024 sample latency would really raise the CPU. What kind of latency are you getting out of your convolver?
The code I added to Mythtv and Xine corrects for most of the latency of the output as part of the audio driver - using a seperate PC might mean the latency wasn't obvious to the player and I would have to add AV sync adjustment code - is this already in most windows players though?
Commercial Plug
I am working with an Italian firm to distribute a commercial filtering standalone box. It has a nice gui and comes with varying amounts of outputs. If anyone is looking for an off the shelf solution (and this is DIY ground) then please do get in touch.
The only machine which I owned which was really terrific was an Antec Sonata. I put in a fanless PSU (which runs pretty hot and I tried several because they all failed fairly quickly...). The other fan was a 120mm big boy on the back which spins really slow and was absolutely silent.
The Sonata was near inaudible in my room from very close and totally quiet from a distance. Also the cooling was incredible with temps at 30c or so with only the single 120mm fan at the back (compared with my Coolermaster boxes which have 7+ fans in them and the machine is much hotter!). Clearly design plays as much of a factor as number of fans!
The worst case I owned was the Claritas Strata fancy HTPC case. I have one for sale if UK buyer wants it. Lovely looking box, but zero silencing.
Also although most of the desktop style cases look best for HTPC the cooling is much, much worse than with a tower case. Also the tower case usually ends up on the floor, but the HTPC case ends up nearer ear height (and high freq whine is more audible in straight lines). So if looks aren't important then tower is the way to go
Antec seems to be a really solid choice if you just want something which works! I was very, very pleased with my Sonata case. I sold it and bought the Claritas case....
I am now using a "Heatsink Case" from HFX. It weighs a ton and has no fans as standard, just lots of heatpipes.
To be honest I think the "no fans" thing is a risk if you care about drives failing though. I added a small low speed fan just to get a small amount of air moving inside the case. Even a tiny fan will drop the temps 20-30C so it's worthwhile. Anyway, it's currently the best choice for me
OK, so now tell me: How have you found the Lynx compared with the RME 9652? Seems to me that they are going to be identical with the RME being 1/4 the price? Do you hear an difference bearing in mind you are spitting out digital?
How are you doing volume control with so many DACs? What would be perfect is if the Apogee had a master volume control (which didn't work in the digital domain)... I had to build a multiway attenuator using a DACT stepped switch - I have a remote control on it which allows me to change volume control from the couch. In practice I set it roughly to max volume that I need and control the volume using digital volume control in the player app - sure it looses some precision, but the RME 9632 DACs are around >110db so I hardly care if I loose a few bits at low volumes!
What kind of filters are you running now? I am using Brutefir at 44Khz with 65535 tap filters and it's tiny amounts of CPU compared with the amount needed for resampling. Brutefir does partitioned convolution and running at 2048 sample latency is ok, but dropping to 1024 sample latency would really raise the CPU. What kind of latency are you getting out of your convolver?
The code I added to Mythtv and Xine corrects for most of the latency of the output as part of the audio driver - using a seperate PC might mean the latency wasn't obvious to the player and I would have to add AV sync adjustment code - is this already in most windows players though?
Commercial Plug
I am working with an Italian firm to distribute a commercial filtering standalone box. It has a nice gui and comes with varying amounts of outputs. If anyone is looking for an off the shelf solution (and this is DIY ground) then please do get in touch.
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