Bifwynne ...
Yes, its the CD-7 with the upgraded power supply and tube upgrades. Big jump in sound over the stock CD-7. In fact, quite amazing. I have it on good authority that the newer CD-6 is more analog-like ... and it has no tubes.
Dbarger ...
Yes, you're correct. The top WILL fit on with the KT-150's in place, but just barely. Even so ... leave the top off. The amp sounds better sans the top ... just like turning the meter lights off. Same thing for all of ARC's display lights.
Also, just in case you folks haven't seen this in some of my other posts; move the tube dampener rings up to as close to the top of the tubes as you can get them, and be sure that both rings are solidly touching each other. This provides for a nice overall improvement in sound.
Happy listening ...