WHY IS A TUBE AMPLIFIER BETTER?
Tubes sound better because their distortion products are more musical. Tubes provide a more appropriate load to transducers. Those are the fundamental reasons why tubes simply sound better. Tubes are voltage amplifiers as opposed to transistors which are current amplification devices.
WHAT IS THE ADVANTAGE OF A TUBE AMPLIFIER?
solid state is more efficient, smaller, lighter, and can have far more power than a tube amp, but also have limited dynamic range. they are quieter regards signal to noise ratio. the lower impedance of the circuit reduces their tendency to be affected by stray capacitance, inductance and electromagnetic interference.