A thread update for future readers.
The little 30 W Pass amp just killed the 400W McIntosh. The Mac did help address the bass issue (although not a ton), but was bested in every other dimension by the Pass. Putting the Pass in the system was like lifting a veil off the music. You could hear so much more detail, a much better soundstage, and an elimination of a lot of glare in the sound. So much more delicate and natural. No contest between the two products for me.
Anyway, after this experience made me fall even harder for the INT-30A, I decided that maybe adding a sub to my system might allow me to keep all the benefits of the XA series, but also make up for the bass deficiencies I've had. Although I'd have preferred to have tried a Thiel sub, I ended up getting a decent price on an REL Storm III. I have to say that I'm extremely impressed with what this sub did to my system. Like others have commented, adding the sub opened up the soundstage and added depth to the music. I also watched Salt and listened to Tupac's All Eyes on Me (well recorded quality rap, btw), and the sub really made up for the previous bass deficiencies that had made these types of material feel flat and lifeless before. Yesterday was really the first time I've been fully satisfied with the stereo since beginning the upgrades in December.
I did end up purchasing an X250.5 to compare to the INT-30A, but only because I'd initiated that process before getting the sub. I'm actually very satisfied with the current setup and probably would have quit amp shopping if another day had passed. I will update the thread, however, after comparing these two amps.
Thanks for all the feedback folks.
