This would be running to Crown XTI 4000s I've repaired, I have two but if this is the way I'll buy more. I have other QSC amps that run the subs, ...
Are they in the same rack?
AFAIK, Crown cooling fans draw from front to back and QSC, from back to front. Depending on their location, I'd be cautious of one amp "breathing" the exhaust of the other.
Dave