I dont even understand how a 5 watt amp could be big enough to have tubes in and how it could be so loud. My friend has a 10 watt solid state amp and thats not too loud !
By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.