Amplifiers for looping

[SoundFNR@aol.com]

Part One
  What makes a good amplification setup for loops in a 
live context ? (any recomendations?)
Guitar amp for  sound character.
Or a PA type system to accurately  produce
a multi-layered effect.
Stereo?

Part Two 
  How does the sound  'quality'  effect what 
the player does with the loop?
 
Andy (UK)