Which compressor? Usually whatever I have at my disposal. I don't do much live work anymore but when i do it's usually a DBX unit of some sort whether it be a set of 160as, 1066 (yeah really), a driverack or some other pieces of shit. On the other end of things I've used trakkers, 1178s, and an RNC run through a line balancer. I'm not as picky in live clubs as in the studio, hell, even the 1066 will do. Sometimes killing a lot of out of hand transients is what is required.