Solid state usually sounds thin, and not good to the ears.
Tube amps sound warm, beautiful, and easy on the ears.
If you have a solid state amp at 100 Watts, and a Tube amp at 25 Watts, the tube amp will sound louder than the solid state amp at the same volume (considering that the volume is over 2).
Basically, just get a tube amp, they sound wonderful. Try the Fender '65 Deluxe Reverb.
That's all you need to know...
Well, you can't really just play out of a head only. There's not enough driving power... You can do the Head w/ cabs, or you can just do an Amp.
Basically, the idea of heads and cabinets is that you can get the tone out of the head, the driving power out of the speakers.