It's not 20 watts on a tube amp vs. on a SS amp. It's 20 watts on any amp vs any other amp. Watts per channel is measured under certain conditions which can be varied to get to the desired marketing result of a spec.
You need to listen to the amps you are comparing, ignore the specs, unless they tell you some situation where they won't work, like speaker sensitivity under 90dB. If you never turn it up, maybe you'll like tubes.
You need to listen to the amps you are comparing, ignore the specs, unless they tell you some situation where they won't work, like speaker sensitivity under 90dB. If you never turn it up, maybe you'll like tubes.