PC-based server versus network-based player

[hillbear]

I am new to PC audio so need to pick the best brains on here. It seems that there are 2 different ways of approaching it - METHOD 1 is to put your resource into the PC itself then output via USB to SPDIF converter to DAC or METHOD 2 use network-based player such as Squeezebox feeding DAC, with basic PC used to control it. What is the best approach for best audio ??? I am sure they both have their advantages/disadvantages but I have yet to hear any real expert opinion on which sounds best (for similar budget). What do you reckon, guys ???

[soundcheck]

Consider the Squeezebox, e.g. SB Touch, a PC running Linux with
special focus on Audio. It's a PC and high quality audio interface
in one box.

It'll take quite some effort to achieve the SB Touch performance on a comparable audio PC.

It's much easier to tweak the SB. E.g it requires just a little linear 5V supply upgrade or you can try my toolbox.
Try that on a PC.

Here you'll find some useful information what to to with a normal PC: Cics CMP2


The real problem is that the audio interfaces (external DACs) can't cope with source originated jitter and noise.
If all those designers would do a better job, we should be able to hook up any bit-perfect stream from
any digital source without facing source related distortions and differencs.

Slowly but surely manufaturers start taking measures. E.g. galvanic isolation, multi-stage de-jittering, intelligent reclocking.

However. IMO one reason why there is a lack of movement in the market: There are only certain manufacturers who rule
the market with their propriatery licensed interface SW. This you'll find implemented in e.g. many USB audio interfaces.
You bet those suppliers are not interested to move on as long as they can sell their license.

[pedroskova]

I went PC because, in addition to acting as music server, it also functions as crossover, equalizer, and ambiophonics decoder - try that with a squeezebox.

[aazeez1975]

Squeezebox does equalizer and ambiophonics decoder using Inguz DRC plugin. as for the crossover you can alway try minidsp 2*8. If you wanna go PC route please knock yourself out, but in the end you'll come back to non-PC based solution, and I am talking from experience here.

[Javin5]

Originally Posted by soundcheck

It'll take quite some effort to achieve the SB Touch performance on a comparable audio PC.....

The real problem is that the audio interfaces (external DACs) can't cope with source originated jitter and noise.

When you talk about the audio quality achievable with a PC, do you mean an arrangement where SPDIF is taken from a PC internal soundcard and fed to an outside DAC? If this is your comparison, then yes, I tend to agree.

However, if you take a PC USB-feed to a well implemented, galvanically isolated, asynchronous converter with an independent, low-jitter master clock, then this is a different story. Such a scheme should have a potential at least equivalent to the SB-Touch. Any experience based on actual comparison would be very helpful.

[aazeez1975]

Well my problem was that my PC was connected to the same power outlet as my audio equipment and I can hear it on my speaker. No audio cable connected and the PC was not running. The only remedy is to run an extension from a different outlet.

My setup was running a JRiver MC with touch screen Acer monitor to mimic Meridian sooloos system. It was a 4 way active setup with 3 way floor stander and stereo sub. Everything was passive i.e. no fans and Lynx card. I invested around $2k on the setup.

The good thing is that I re-used the PC as a Media Center in other room.

Now I am running SqueezeBox Transporter with DRC and couldn't be happier crossover duties are with MiniDSP at the moment but I will be moving to a passive speaker system and removing MiniDSP from the chain.

For $2000 you can get DEQX Express and Tact (Used). There are so many options out there that it is really not worth to take the PC route, and explain your spouse how everything works in the end.

Best option right now is to get a MiniDSP 2x8 apply room correction and cross over filters using biquads and call it a day.

[Pano]

I tried a few things and finally went with a PC and soundcard. Just a cheap reconditioned Dell I got on eBay for about $90. I did add a USB hard drive and a sound card that has optical out (and a SPDIF header).

JRiver is the player and I can control that from any computer in the house with a choice of interfaces. The music files could reside anywhere, but it's convenient to have them plugged into the Media PC. A mirror is on my main PC where I do the ripping.

A great system for a low price.

[soundcheck]

Originally Posted by Javin5

When you talk about the audio quality achievable with a PC, do you mean an arrangement where SPDIF is taken from a PC internal soundcard and fed to an outside DAC? If this is your comparison, then yes, I tend to agree.

I'm talking about any PC based audio chain incl. Squeezeboxes - Touch in particular , which are nothing else than special purpose computers.

I havn't found any audio interface yet which, would be immune against distortions caused by those computers.
If it is SPDIF or USB or internal cards or network streamers, it doesn't really matter, they all pick up distortions. And not always through the obvious front door.


Don't get me wrong. I'm not saying that the todays achievable audio quality from a computer based audio system is bad by the way.

I do believe or better know that nowadays a lot more people have a chance to enter audiophile spheres at a fragment of budget as it used to be.

Originally Posted by Javin5

However, if you take a PC USB-feed to a well implemented, galvanically isolated, asynchronous converter with an independent, low-jitter master clock, then this is a different story. Such a scheme should have a potential at least equivalent to the SB-Touch. Any experience based on actual comparison would be very helpful.

It's very hard to compare interfaces such as "USB" vs. "SPDIF" alone. A lot of other factors need to be looked at. USB interfaces can be implemented in
a thousand different ways. Add another thousand ways of implementing SPDIF, recklocking schemes, isolations, powering, clocking, board layouts, asf asf.

I used to run an isolated USB DAC and heavily tweaked PC. Now I'm
fiddling around with a Squeezebox Touch and SPDIF.
The SBT I consider - without applying modifcations - as poor as any other basic PC based Transport.
It's even worse. The network has quite an audible impact on its performance.
You don't have that problem on a standlone PC based machine. With these you start up your RAM player and you're set.

However. With a bit of tweaking the situation can change radically - on the SBT at least.


And - forget those marketing phrases about asynchronous USB DACs and master clocks.

Those asynch USB DACs pick up jitter as any other DAC, it's the amount which is usually slightly less. You find a million posts about how great
Pure Music/Amarra works and that people experience improvements on their top end asynchronous audiophile USB-DACs with slightest changes made to that player software or operating system or HW of that transport.
And that's what the marketing message of async USB DACS actually promisises not to happen. Forget it.


The key subjects to be looked at in all these discussions are IMO the
audio-interface receiver stage, it's reclocking or jitter suppression
scheme, avoidance of intermodulations, it's power supply and isolation.
The key question really is - How well does the interface section isolates from the source and how well does it feed the actual DAC.


The EXAU2I guys with their quite nice propriatary (and Windows only) multichannel asynch USB interface implemented I2S isolation as you might know. Great approach.

However. That isolation chip itself was and probably still is causing 250ps jitter (under lab conditions) on the I2S bus. That's not what I call high-end.

Though there is no free lunch. At one point you have to go for the better compromise , the lesser of two evils. And at that decision point jitter defeated noise, which is fair enough. Let's hope they get this resolved with Rev 2.

FPGAs and PICs on the actual audio boards are also pretty tricky to handle. These devices are usually sources for different distortions and can interfere with the sound critical parts.

And not to forget the SW. You wouldn't imagine how complex the whole SW
handling (OS/drivers/player/firmware) is. I read about a pretty generic problem, where quite some SW-players were doing faulty float2integer conversions - a very basic subject causing non-transparent bit streams.

I'll leave it for now. Gotta run.

I can just advise you - watch out. It's getting more an more complex to really see what's going on out there. Meanwhile I do know
quite some people who are piling up dead audio interface bodies.
That we should avoid.

And one thing I experienced. If you think your systems peforms etremely
well at ony point. Don't touch it anymore. The next SW update can easily change that situation - usually into the wrong direction.

[Javin5]

Hi Soundcheck

Thanks for your detailed reply. Yes, I fully agree that this is very complex, each part done by different people, difficul to impossible for anyone to have a total overview and knowledge about all the parts involved.

And yes, I was thinking about an EXAU2I feeding a Buffalo DAC. Music would be stored on the PC, no need to to even connect to the Internet. The PC would be fully silent (except the HD) and control would be via a large touchscreen. Actual ripping would be done on my office PC to an external HD, from which the files would be transferred to the music-PC in the living room. The external HD would also serve as a backup. So this would not even involve a network. But as you say, there are a zillion different possibilities. The really nice thing about your solution is that you can control it via an iPad. And I could imagine that you have a lot less interference and noise in a SB-Touch than in a PC. Even though the SB-Touch really is a PC, its functionality is reduced to the bare minimum required, and this helps to cut noise, etc.

With the SB-Touch, I don't see how I could avoid a wireless network, and that worries me a bit. So I`m not sure at this point which way I will finally go.

[dwk123]

Originally Posted by pedroskova

I went PC because, in addition to acting as music server, it also functions as crossover, equalizer, and ambiophonics decoder - try that with a squeezebox.

I ended up doing both, sort of. I couldn't come up with a PC playback interface that worked well headless via remote control. So, I feed the spdif output from the squeezebox into the PC which then does the xover/eq and then outputs via a Steinberg MR816.

I use a hardware SRC unit slaved to the word clock of the MR816 so that I don't end up using a PLL recovered clock for output. Not entirely ideal, but I 'need' to support at least 44, 48 and 88 rates (and probably 96 eventually as well), it was more practical to run the PC at a fixed rate. (88k for SACD converted to PCM via an Oppo)

IMHO for all the annoyances of the server software, the squeezebox is a pretty darn nice setup. Despite being a long-time PC-based audio guy, I'd find it pretty much impossible to justify a PC based system over the squeezebox if you don't need xover capability, and as it turns out maybe even if you do :-)

Originally Posted by aazeez1975

For $2000 you can get DEQX Express and Tact (Used). There are so many options out there that it is really not worth to take the PC route, and explain your spouse how everything works in the end.

Potentially interesting options, albeit with a different set of trade-offs from a PC-based system. I'd be willing to bet that my current system with the MR816 at least equals and likely exceeds those, and ran about $1k for the pc hardware and interface. It still leaves the dsp/filter generation process though, which is where a lot of problems can crop up. I'm pretty happy with where I ended up - 'external' sources and a single-purpose headless (more or less) PC - although that's definitely not where I thought I was going to start with.