Busted out the VP for practice the other day to test out the Acoustic 360/300+301 cab (unpowered version from the 371), and man does that combination just WORK. There is something about the Acoustic Preamp that just seems to be made for the Thunderbird. The growl just seems to explode, while being able to keep the lows tight and not overwhelming. I used my Grecobacker too, and it sound fantastic as well, but the Acoustic and Thunderbird are just made for each other, more so even than the T-bird and Sunn or T-bird and Hiwatt. The Sunn and Grecobacker have a similar thing going on, they just pair perfectly.