Watts is watts - that is the old wife's tales that a 50-watt tube amp plays louder than a 200-watt SS.
People still believe this stuff in this day and age blows my mind.
@botrytis The reason that myth persists is due to how tube amps distort. They have 'soft' clipping and when doing so can generate just enough higher ordered harmonics so that they will sound louder than they really are.
This is because the ear uses the higher ordered harmonics to sense how loud a sound is. As long as the more powerful solid state amp is only a few dB more powerful (200W is only 6dB louder than 50W) this illusion caused by distortion masquerading as power can hold together.