[richardyc]

I recently got a Music Hall DAC 25.3, and like others, I felt that the bass was a little weak with the stock tube, so I replaced it with a gold pins JJ e88cc tube.  The bass is a lot better with this tube, but I was still curious how much better this DAC could sound, so I bought the 3 (matched pr + 1) Burson opamps to replace the 2604 and 2 2134 opamps.  After about 100hrs of breakin with the Burson opamps, I thought the highs and mids were slightly smoother, but the bass was back to being on the weak side again.  Actually I heard that right away, but I thought maybe the Burson just needed the 100hrs break in time, but after about 100hrs of break in, the bass just sounded like I was using the stock tube, all the benefit of the jj e88cc tube was gone. So I tried a diff combo of Burson opamps with the stock opamps to see if I could get some of the bass back.  To make a long story short, I think the DAC sounds the best when it's with the 2 matched Bursons replaced the two OPA2134s, and continue using the stock OPA2604, this combo has the smoother highs and mids and bass gained from the JJ e88cc tube, and that's how I have it setup right now.  all in all, I spent about $750 for the DAC + all those extra parts, If I have to do this all over again, I'd probably get a diff DAC in the $1k price range and forget about all the tube and opamps rolling. Just my 2cents. 

 

[danmagicman7]

If you don't feel like upgrading the tube, you can take advantage of the solid state DAC by buying XLR->RCA adapter cables, then plug into your amp.
 
Just utilize the DAC as solid state with the option of a tube output.  Sounds awesome without any tube in the way of the output path.