I did rig it briefly as a non oversampling dac just to hear the difference, and the opacity/harshness was gone but so was the upper treble. I did this mod by attaching jumper cables to the leads of R35 and R36, tapping into the output of the dacs before the op amps. The positive lead from each resistor was connected through a 3uF Northcreek cap for DC isolation, then into the interconnect to the preamp. I made no other changes such as removing the op amps.

I would appreciate it if someone who knows more about dac design would look at the link below and tell me if these resistors are the correct place to tap into the dac chip outputs. There's a link to the schematic in this article.

http://www.audiodesignguide.com/DAC/dac5.html

Yesterday afternoon, as a last resort, I removed the OPA627 op amps and reinstalled the OPA602's. After a night of repeating the breakin track from the Stereophile Test CD #3 the harshness is now gone. Go figure! This isn't a bad DAC, especially when you consider the $135 price tag. The bass and lower midrange are a bit more pronounced, and is about 5dB louder than my Scott Nixon tube dac, making it an especially good choice for anyone with bass shy speakers like Fostex single drivers and many horn speakers. The soundstage is more convincing than the SN dac - wider with a slightly better separation and isolation of instruments.

I wish I could say I hear an improvement, but it's so hard to tell that I will just rely on my faith that a quality metal poly cap sounds better than a 50 cent electrolytic.

http://www.liteaudio.com/2005-1-22/2005122154743.htm

What are the white rectangular parts near the output jacks? They look like rectangular metallized poly Wima-type caps but I don't recognize the information printed on them. Are they the "Full Balance LPF using discrete transistor components (four LPF)" described in the DiyClub DAC-68 site? What is an "LPF".

http://www.liteaudio.com/2005-1-22/2005122154743.htm

The white parts look like capacitors to me. Can you see from the traces what they connect to?

Interestingly, I looked at the Diy Biz web page this morning and the DAC-38 is still included in the list of offerings, but when you click on it the page that comes up says "There are no products to list in this category". Are they playing games with my head, or is it divine providence delivering me from temptation by removing the source?

http://fredt300b.smugmug.com/gallery/132868/25/36512237

I have reached a final conclusion about the DAC-AH: It sounds very nice, and I prefer the overall sound to the Scott Nixon dac and the Onix XCD-88 player. It is voiced toward the warm side, which probably isn't the best match for my tube electronics and warmly voiced line arrays. It would be a super choice for a solid state mid fi system that's voiced toward the bright side - It won't attenuate the treble at all, but it will improve the treble/midbass balance. It might also be good in a system using single driver speakers that tend to be a bit light in the bass.