I've heard ENGL is the way to go for low to high volumes, I also heard that Rivera is pretty good too, is this true? Any other companies ?
most high gain amps sound fine at low volumes, they still sound better at high volumes, but they'll give you high gain sounds either way.
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Peavey is all good, even my VK sounds pretty nice at low volume.
Jackson RR3 with EMGs!
B.C. Rich KKV
Yamaha F-310 Acoustic

Digitech Bad Monkey.

Peavey Valveking 112