feedback matrix loops

[Kriist@aol.com]

ive spent alot of time browsing David Myers page (pulsewidth)this weekend 
and 
have taken a keen interest in this idea
this have the fun time i had last week taking the out from my stereo 
delay/reverb pedal back into the input and getting a world of sounds(then 
again, that pedal is broken anyhow so it makes a world of sounds on its 
own)
what sort of commercial mixers(pref rack mountable)come close to the ideal 
matrix?
i suppose just lots of aux and routing capabilities?

rodrigo