Tube Power vs Solid State Power

1. IMHO height-sensitive speakers or mid- sensitive speakers in small room are must.
Powerful amplifier with low sensitivity speakers is the wrong solution. Voice coil heating causes compression. More power you give  - more compression you get.
2. Height-sensitive speakers work best with low power simple schematic triode tube amplifiers SET or push-pull. This combination gives a real transparency, micro dynamics, musical details, tone naturalness, natural life like dynamics.

Triodes have much less distortion and amplification element vs any type of transistors.
Plus triodes have very low 3rd order harmonics vs transistors and pentodes.
To get low distortion in transistor amplifier a deep global feedback should be used. 
This feedback shifts distortions to higher orders. Out brain is super sensitive to height order of distortions. Sound become more harsh, macrodynamic is sufferings, instruments tone become flat and artificial.
Also transistors have thermal distortions that tubes don't have. This issue solution is class A.

@flasd Distortion at clipping is why this myth persists. Simply put, tubes can overload quite gracefully while transistors cannot. So you can have the musical waveform briefly overload a tube amp and you may not notice. But you will if that happens with solid state! In addition, 3dB isn't much of a difference to the ear, but to an amp its a doubling of power. For this reason a tube amp that overloads gracefully might appear to keep up with a solid state amp of twice the power.


One exception might be when you try to drive certain ESLs or other speakers that have a high impedance. Tubes quite often do not lose power into higher impedance, but all solid state amps will. For example to make a Sound Lab ESL play at a certain volume, you might need a 600 watt solid state amp to do the job in many rooms. Because the Sound Lab has a 30 Ohm impedance in the bass, that solid state amp might be only able to make about 150 Watts. But a 150 Watt tube amp might make 150 Watts into that same load- and so in that case its not myth; the tube power is more powerful.

personal experiences- an amplifier's output energy has more to do with the design and quality of an amplifier (and preamplifier) than its power rating, tube or solid state, all else being equal.