regal

Just compare a $1000 PS Audio DLIII Sigma Delta to a $200 Ebay Adacom GDA700 or a $150 Audio Alchemy DDE v1.2, its embarassing. I honestly dont see how anyone can listen to the PCM179x chips. Same can be said about the Benchmark. And this 19MK3 Chinese JY build beats them all, even the Pass D1 clone I built. Sorry I don't have any DATA, there is no serial port on my ears Take my advice or leave it, just trying to help people by not making the same expensive mistakes I made. One thing does piss me off about AudioGD, they won't sell you the schematics even after buying the damn thing, I have never purchased anything from a car to a washing machine that I didn't buy the schematics (service manual) for. If it weren't for that I'de try one of there more expensive DAC's.

QC or not, A hardwired silicon filter and a laser trimmed R2R DAC chip sound better than sigma-delta, ask Erno Borbely, John Swenson, Jocko Homo, or Louis Motek what they think about sigma-delta chips. I also have an Audio Alchemy PMD100+1862+Cetoole output (thanks for the board Colin) and this AudioGD is right up there with it in SQ.

What they are doing is pulling and re-using old chips from equipment others throw away. The cost to tool up and reverse engineer a PMD100 or PCM1704 would be exponentially higher than finding junkyard chips. Unless he is selling a million units a years there would be no payback. And yes I veryified that the PMD100 decodes HDCD. Also swapped the chip with a PMD100 from a 1994 Audio Alchemy and they sounded the same. In a decade DAC's like this with a good digital filter and an R2R DAC are going to be like gold, just like old tube equipment is now. Sigma-Delta chips are flat out inferior. As far as stamping a "K" on the (non K) PCM1704's, I wouldn't put that past anybody, even TI !

I rarely post praises of commercial gear as a prefer to build my own, knowing that each component is used in the correct topology is important to me. I am no shill as you can see from my 2000 posts on head-fi. I have to say that this 19MK3 is an outstanding piece of gear. They have done three things extremely well: 1. PMD100 - I'll say it till my death it is the pinnacle of the digital golden age. One day these will be worth $1000 a chip, mark my word. 2. PCM1704K - Erno Borbely told me personally that this is the finest DAC chip ever made, some would argue the AD8162(Jocko) or the PCM63K, but regardless it is a much better design than sigma-delta chips. 3. Zero feedback analog stage - all these $1000 DAC with C-moys on the output make me sick, this is the way to go. Results is that this DAC can convey the ambience of the recording as well as any source I have heard, I can listen to good recordings that that the guitar would sound distant and dull on lesser DAC's but with the 19MK3 the instruments have life! I hope we see a trend toward R2R DAC's in this price range with discrete zero feedback output stages.

I decided to build a SOHA II to hold me over till the Stacker II is done, they Stacker II is basically a SET OPT amp with a solid state circuit acting as the OPT. The SOHA II is the same but the first stage is a cathode follower and the tube B+ / current is restricted.

I used 12SN7's cause they cost about 1/10 the price, this amp when the bugs are worked out will be very veratile.

Someone on the head-fi thread has a 220V PS with 10 mA tube supply, but the details are sketchy, he had to use higher voltage rated transistors above the plate, also changes some resistors, but no one including the modder remembers the details. I can understand as I used to mod/design stuff on the fly and not keep, records. But this SOHA II with about 30V higher plate voltage and 5mA per tube section would be a giant killer.

I decided to build a SoHA II while waiting on the Stacker II project to get out of grid lock. The SohaII is a very interesting design with a few limitations. The tube current is very low, I can only get about 1.5 mA thru each section and the plate voltage is only about 40V. That said this is a terrific sounding amp. I didn't like the recommended RCA 5693 tubes, they were too congested with distortion in complex passages. I switched to 8416's which sound very nice. In comparison to my Bijou this little SOHAII actually has clearer better defined mids, I was very surprised to hear more of the ambience of the recording in voicing and guitar. The Bijou beats it in power handling easily and the Bijou has a better grip on the lower octaves. I believe the Stacker II will combine the strengths of these two amps and we will be building a Zana Duex killer for under $400 buck. Can't wait.

Yea mine had an oscillation in the PS which messed with the buffer, but Alex recently told me there is a new PS and the project will be renewed soon. I can't wait and can't thank Alex enough for all his work for the DIY community. I absolutely love my Bijou. The unique thing about the Stacker II is it will give a pure unmolested SET sound. I still have mine in pieces ready for a new buffer board and PS board. I think I will build a Soha II while I'm waiting, it seems to get good reviews.

Yes but I have several OTL, want to try an SET OPT head amp.

I have been a long time supporter of DIY tube amps. I want to try an SET headphone amp. What I am finding is you can buy a new WA6 for less than building a proper SET amp because the air gapped headphone OPT's cost so much. Is the WA6 a well designed amp, does anyone know the topology? I'm on the fence with this one, any feedback would be appreciated.

When I had my Stacker II running it was the best sounding amp I've ever heard. It is essentially an SET amp with transistors instead of the transformer. There were some issues with the powersupply and buffers oscillating. I understand that this is being correcting and I can't wait, this amp will be a revolution.

I agree with dsavitsk, the Ec99 is a hard sounding tube. I really like the 6N6P in its place.