CD has laid back and uninvolving sound

Dazz...very nice components. The Acoustic arts is a very fine dac but I have never had a piece of tube gear that couldn't be voiced differently by rolling tubes. It looks like the AA dac uses a 12ax7 so if your inclined I would try some different tubes.
I had a conversation with a fellow audiophile at a Christmas party...He said the exact same things about his experience with vinyl vs digital. But for my experience tweaking has convinced me that swapping tubes and capacitors can make a major difference on how a system is voiced.

hi chris:

i will be reviewing herbie's tube dampers, but i have not auditioned the tenderfeet. i have also reviewed dcca cable and owned several versions of his power cords.

i have sold them and am now using ear to ear power cords, and ear to ear speaker cable.

I have been using various damping devices for decades but only recently have I become aware of what the newer types could do. Using 3 small cones under a component can transform the sound. The products I use, Star Sound, have a theory that it is of prime importance to provide a direct path for vibrations to be transferred quickly out of the system to the floor. There is apparently something to this as a recent test of a completely different product found that components siting on it sounded better when they were physically touching the metal pole supporting the system. Be that as it may, the effect is considerable. But not all the cones I have used sounded the same, the Mapleshade are good in many ways but their very large size seems to make the vibration transfer slower. I would suggest to anyone that the purchase of one set of top quality cones is a worthwhile investment to see how they work in your system. But be patient, they need to settle in. I know, this does not seem logical but it appears to be true. Also, they do not give to same result on each component . Sometimes it can provide too much dampening. But overall it can provide a major step up in performance. I bought a rack for my whole system that has them built in and the result is even better. There are many other systems on the market I have not tried, so I cannot say if they would give comparable results. But in any case vibration removal appears to be even more important than we had thought. Do not ignore maple blocks, they give good results also.

If you decide to audition new DACs I would suggest you consider the Berkeley Alpha DAC. I don't have any experience with your equipment and have only heard the Berkeley once when auditioned by a dealer. Like everything else the true test is having an opportunity to hear it in your system.
http://www.computeraudiophile.com/Berkeley-Audio-Design-Alpha-DAC-Review

Accustic Arts actually came out with a SE (special edition) version of the Accustic Arts Reference DAC. According to what I heard from my dealer, the improvements are changing the quality of the PCB boards used and supplying better tubes than those made in China tubes provided with the standard edition. If you want to really max out the performance of the AA Tube Ref DAC, please do try out its matching partner the AA Ref Transport, IMHO it should more matching than the MBL transport. Also recently I upgraded my transport power cord to top of the line Acrolink 9100 power cord (this is higher than the 7100 reviewed here that impressed the reviewer so much that he and his friends bought a couple) and I must say that this power cord really made the music even more involving than before, so you may want to check out the Acrolink 9100 power cord on your transport too