Low gain dac!

George,
 Sometimes you make no sense. OP has freely acknowledged he has too much system gain. He wants to address it by finding a suitable DAC with less output voltage.  This makes sense and is a reasonable solution. 

You like to frequently tout your tech expertise,  ok fine. Why so blatantly ignore his documenting  his'very' positive listening impressions with the Supratek?  You brush that aside because this result (Good sound, we are discussing audio) doesn't mesh with your version of tech dogma.

OP couldn't make it more clear that his audio system sounds better with the Supratek in the signal path. 
Charles 

Less source voltage will = even more hum/noise.
Inline attenuators to reduce the massive gain he has already will give impedance mismatch problems and more hum/noise.
Throwing a good dac aside for one with "at least" half if not less output to rectify this problem, is a sideways band aid fix with other problems that I've outlined.
As I said the amp with 0.7v for full output is the problem if the Supratek is to be kept

If you didn't know.

@charles1dad - Thanks, I don’t understand George either!

I am one that likes what tubes bring to a system, but have decided to have them in the pre amp as tube power amps would need more care and my speakers are 87db, so needs good power, not necessarily many watts, but a good power supply is a good thing, maybe some day I will have tube mono amps, Supratek makes a nice pair, so, maybe that would be a good pairing with my pre someday when I have gone on pension and have more time on my hands.
I made a post in the Supratek tread about when in Bangkok I was so lucky to hear a anniversary Supratek setup with Triangle speakers, the dealer had time for me, and we sat listening to music and talking about Hi-Fi, music and life in general, I think for 2 hours, as my wife was shopping, that was the best sound I have ever heard and today I can lister to even a better pre from Supratek.
Never expected to buy a pre amp all the way from a one man production shop in Australia, but it’s been totally worth it.

Just listening to this https://youtu.be/qsRLRmRogKU
wonderful music, it is YouTube but it sounds quite okey.

Hi @gryphongryph,
I do understand George’s concerns to a point. Your power amplifier is high sensitivity (Only requires 0.7 v input, same as my 300b SET). So obviously your DAC has a surplus of output voltage relative to your amplifier’s needs. But you know that.

I completely understand your decision. Once you’ve found a component that really pushes your music loving soul buttons why in the world would you discard it? You are very happy with your audio system sound quality and that’s a big deal. I believe that you’ll find an appropriate DAC that matches better (Gain/voltage) with your excellent Supratek.
Charles