MP:
You can purchase a complete HDCD/Power Boss unit on the used market for the same, or less, than the expense of adding these features.
The last time I checked (3 years ago) the upgrades were $600, plus two way shipping and both were offered as a complete package.
I do not care for the HDCD/Power Boss version myself as the mods give it a brighter sound (it sounds very much like the 10 and 15 models).
I find the bass to be tighter (but there's less of it), and though there is increased detail and dynamic response the warm/liquid quality of the version II is pretty much lost.
I have used a couple of outboard DAC's (Bel Canto 1.0, 1.1) with my CAL and it does make for a good transport, however placing the stock version on a well designed shelf and adding a decent after market power cord also works wonders (this is what I currently do). If you don't want to hassle with a new shelf/base, then try replacing the stock feet with large E.A.R. footers (these are inexpensive and sound better to me than any other cone/soft footers that I tried with the CAL). I also have some other footers that are a round ring (probably E.A.R. material) with a ball bearing squeezed into the center. These also sound good (don't shift the overall balance too much), but I don't know who makes them. Bruce (Brulee here) gave them to me and perhaps he or JCtubes know where they can be purchased. Both footer types help to increase dynamic swings in the music and they also clear up the bass a bit (subtle changes, but they are exactly what the CAL II needs).
Leveling the CAL's transport mechanism would also pay off in a setup such as yours as this will further extend the HF's (the Thiels and the AI are not rolled off in this area). Once you level the shelf further adjustments can be made via four spring mounted screws inside the unit (just avoid locking them down as they need to be sprung, and be certain that the tray clears the opening on the faceplate).
If the HDCD/Power Boss version interests you though (lot's of people do like this model) then maybe pick up a good used unit and then resell it if it's not the sound that you are looking for?
