I'll have to agree with the the great, but "different" sentiment. I generally use the M4 through a 2/50/2 (w/JJ KT77s) and it's fantastic, without question. Sometimes I run it through the series loop of the MOD50 (w/Svet 6550s) and that too is really great, and seems a bit more interactive than the VHT. Same general comment regarding the seminar head loop (w/EL34s). Recently I've been messing around with running it though the power section of an SLO clone. For as much a the SLO is known for it's preamp sound, the power section may be my favorite of all. I'm running Ruby 6L6s and it uses the O'Netics Hi-Def output transformer. I know folks view the SLO as kind of a singular sound, which is legendary, but pairing the Eganter mods with the SLO output is spectacular. Not really addressing the OP question, but either choice will provide great tones. Obviously the M4 will give you more options given the four slots, and you can pair it with a stereo power amp which may be desirable depending on what you're intending to do with effects.