Well, far from being an electronics engineer I could only say that rather than matching two boards as wholes - that's what is needed - it seems more reasonable to rely on the very good THD and SNR characteristics of the circuit, and accordingly adapt the interface of the rest components so that they continue to perform the way they where designed to. It could be done with bal/unbal transformers or - what I' ll do - use only positive phase of the DAC output fed through DCG3 to the positive phase input of my amps with negative phase input grounded. I don't even know how it will sound until I test it though...
I believe it all depends on the next stage input impedance for this to work properly. It has to be either absolutelly matched - less than 1% - or, more realistic, very high impedance. Thus an input transformer or a tube stage with grid chokes.
When the noise floor is adequate in a same circuitry type system no matter if arranged in SE or BAL transfer the apparent resolution will be the same. Just because in practical systems there are some residuals, especially magnetic field AC common mode noise, BAL is doing better and it can be perceived as a better sounding architecture per se but its mainly a matter of SE execution and interference circumstance. BAL is the de facto battle shield in the noisy and unpredictable pro reinforcement world. At home when all is done well in the boxes and the mobile phone is at a distance, no worries. Use magnetically shielded transformers and coaxial shielded signal wiring in SE. Ground well also and it can be very quiet.
True, balanced signal transfer should remain balanced impedance from start to end. Although the CMRR does not collapse to zero with imperfections it can range in large dB scale of success.
This is what I had in mind. You can use a dual series/shunt stepped attenuator with each shunt inserted between the + and - phases of a channel and .1% or better series resistors.
Thanks.
nash
Evening all 
I draw and etched one of my DCSTB(Psu) board's today... Long time since i tried that last... but it went well
-I must say, i really like this part of diy, creating one's own pcb's... Allthrough i am not sure i can make the pre. pcb, i will give it a try. Thing is, that the layout and trace clearance etc.. is close to what i can archive by hand.
I ordred all the part's for both dual-psu's, and the Pre. today; so now i have to wait for the snailmail to arrive her in DK.
I hope you all enjoying the sunday too?
Jesper.
I draw and etched one of my DCSTB(Psu) board's today... Long time since i tried that last... but it went well
-I must say, i really like this part of diy, creating one's own pcb's... Allthrough i am not sure i can make the pre. pcb, i will give it a try. Thing is, that the layout and trace clearance etc.. is close to what i can archive by hand.
I ordred all the part's for both dual-psu's, and the Pre. today; so now i have to wait for the snailmail to arrive her in DK.
I hope you all enjoying the sunday too?
Jesper.
Attachments
The other day I had the chance to visit salas at his house and listened to his dcg3 preamp in his system.
I have listen to his system before with his 6V6 pre, but his new preamp was definitely a step up in sound quality. The first thing I noticed - as I did on my own system with a a point to point built I did - was the bass. Now it had more control and extension. This was a big improvement from before.
But it was not only that. We had more resolution in the mid and treble, but with absolutely no harshness. Soundstage opened up a lot too.
All these qualities help us to fine tune his speaker crossover, which I think is completed by now.
What else can I say? I know that salas did a lot of research in this and it shows.
I only hope the teabag will send the PCBs soon as I have on hand or on order most of the parts!
I have listen to his system before with his 6V6 pre, but his new preamp was definitely a step up in sound quality. The first thing I noticed - as I did on my own system with a a point to point built I did - was the bass. Now it had more control and extension. This was a big improvement from before.
But it was not only that. We had more resolution in the mid and treble, but with absolutely no harshness. Soundstage opened up a lot too.
All these qualities help us to fine tune his speaker crossover, which I think is completed by now.
What else can I say? I know that salas did a lot of research in this and it shows.
I only hope the teabag will send the PCBs soon as I have on hand or on order most of the parts!
Despite the beauty of tubes (the looks, the feel and the analogue value) nothing can beat a properly designed SS device... I have made the same observation and change in the last year.
I was always convinced that my tube headphone amplifiers were "it", but lately they have been pushed from the front row of my shelf by amplifiers sporting Toshiba Jfet's and Mosfet's.
More clarity, less distortion, sweet timbre, merciless bass, extended treble...
I was always convinced that my tube headphone amplifiers were "it", but lately they have been pushed from the front row of my shelf by amplifiers sporting Toshiba Jfet's and Mosfet's.
More clarity, less distortion, sweet timbre, merciless bass, extended treble...
That some endorsement!
Does it make sense to use a Slagle AVC instead of a volume pot either before or after the DCG3?
I think only before, as the output impedance is very low and there is no noise to attenuate.
Now, if it sounds better or not only a comparison with a pot will tell.
You will be in a better position to tell the real difference because your 6V6 preamp is built more extensive and expensive than mine and maybe my newer amps were too demanding an impedance for it. It had beautiful tone in the system though and I was a bit afraid I would lose it with the drive and impact of the new preamp but thankfully not. I tried to keep DCG3 very simple SE signal path of all FET along with high bias for that. A "First Volt" minded SS preamp to make a pun.
The 6v6 has a sound I love. It is worthy of whatever you throw at it and I will always have one in my arsenal. If this preamp challenges it, then I am sure it will sound great. I know all your amps are thoroughly vetted when you release them and I always have confidence in what I will get. I have come to appreciate the differences as much as anything, and often times, system synergy matters as much as anything. I have had great components sound bad in the wrong combination. I have never figured out the formula tht leads to audio Nirvana. It iis a fickle hobby. Anyway. Finally got around to ordering parts so hopefully mine is done in month or so. I would say a week, but I tend to be reallllllll slow.
. If this preamp challenges it, then I am sure it will sound great. I know all your amps are thoroughly vetted when you release them and I always have confidence in what I will get. I have come to appreciate the differences as much as anything, and often times, system synergy matters as much as anything. I have had great components sound bad in the wrong combination. I have never figured out the formula tht leads to audio Nirvana. It iis a fickle hobby. Anyway. Finally got around to ordering parts so hopefully mine is done in month or so. I would say a week, but I tend to be reallllllll slow.
It has its own old thread in the tubes section of the forum http://www.diyaudio.com/forums/tubes-valves/102352-6v6-line-preamp.html