Looper for minimal music

[Andreas Berg <berg@brainticket.de>]

I would like to make some a rather experimental "kind of minimal music" 
thing with "phase shifting" and i am looking for a looper or a setting 
of different looping-devices to realise this.
It's about recording a loop, copy it to another track and change it's 
tempo or do timestretching on it to bring it out of sync to the original 
loop.
The whole thing would be mainly about copying one original loop and 
modify it a bit several times and let all the variations play 
simultaniously and free (unsynced and as independent tracks).
(http://en.wikipedia.org/wiki/Phasing)

I already read a lot about all the loopers that are on the market (and 
also about the legends that are "out of stock") and i think none of them 
is really suitable because it is always something missing 
(multi-tracking, timestretching, tempo control of single tracks ...).
So another idea is to bring different loopers in chain but i actually 
have no clear vision how to do that and what the best devices for that 
would be as i could maybe even combine their features in this solution.

I'm thankful for any advice... (maybe there is even a solution i never 
thought of like using ... instead of loopers. But it has to be a 
hardware solution - i don't want to use software)