Several of you who posted must not have had direct experience with the amp. You guys are so wrong. If you even did a search, several people do run it at 1 ohm.
I have a ZX 2500.1 and ran it full gain at 1 ohm for testing on an RL-p today. It's taking it like cake and it is not a current hog. I ran it half gain at 2 ohms for 2 months and all I have is 1/0 and big 3 with an kinetik hc 1400 under the hood and a measly 90A stock alt and I got slight dimming. My Treo SSX 1500.1 put out less power and sucked more current. I don't recommend .5 ohms, even for burps, it won't like it. Not to dump or anything, I'm actually selling my ZX 2500.1 that has been used for only 2 months and I'm looking to upgrade, so PM me if youre interested.