About 25 years ago, I had an early 70's era SVT that I loved. 5 years ago, I had a deal with Ampeg and to be honest, I hated the sound. I tried 4x10's, 1x15's, 8x10's pretty much every combination of cab you can imagine with the SVT 4Pro head and the SVT Classic head. Both heads seemed under powered compared to their ratings. I usually had to turn the volume up at least 3/4 in order to hear myself with the band. The cabs didn't project well and I could never get the tone that I wanted. I have since switched to GK and have never had the volume past 1/3. My tone is better, much more clarity and punch.