As far as specs go, output power on these is limited by the choice of output device. If you limited SS amps to a specific output device, class A excepted, you would find that the output power was similar as well. That's why when Sanken came out with transistors with integral thermal sensors and everyone started using them, all of the amps were around 60wpc.
If you mean feature set, that is related to marketing and most amps, tube or solid-state, don't have tone controls, mono switches, phono stages, power meters or even tape monitors any more.
If you mean feature set, that is related to marketing and most amps, tube or solid-state, don't have tone controls, mono switches, phono stages, power meters or even tape monitors any more.