Low gain dac!

Try a $49 Schiit Sys as you can send it back

But at the moment you would have so much distortions/noise because your shunting >90% of the dacs signal down to ground, only then the re-amplify it again noise/distortion and all.
Cheers George

Went on EBay and bought 1 pair of each (Harrison Labs and Rothwell) looking forward to try them out.

I had same problem with a Bruce Moore preamp with Goldpoint step volume control. Each click was to much gain, either to loud or not loud enough. I couldn't go past 8:00 or 8:30. My suggestion may not help but but I'll give it a shot. I had Goldpoint suggest a couple resistors to put on the volume pot and and after I installed them I could go to 1:00. It was a very easy solder job. Maybe you could install a new volume pot with more steps but that may be to drastic. Why is millercarbon so mean?

Essentially the attenuators are resistors that will decrease sound pressure levels.  They come in various values i.e. 4, 6,10 db of reduction even higher values are available . @gryphongryp the Supratek seems to provide a lot of positive attributes in your system. No wonder you want to retain it. Just curious if you've tried a passive in your system for comparison?  
Charles 

What value db attenuators are you trying?
Charles