I have an absolute tank of an amp that would be perfect for your application. Its a Diamond D6 1000.1 in 9/0 cosmetically, and thats being slightly ****, and 10/10 functionally. Its ratings are 250@4ohms, 500@2ohms, and 1000@1ohm, but these were underrated and at one ohm you could realistically get upwards of 1200 watts. So, at 1.5 ohms, according to the specs, you will be looking at 750 watts. The gain knob(as well as everything else on this beauty) works fine and headroom is a lovely thing!
I wish I had some pics but I'm at work now. This line of amps were overbuilt, underrated and very high end. They used 8awg cables on the internals. It has a huge aluminum heatsink with large fins. You could literally stand on this beast and cause no damage whatsoever. I almost forgot to mention it's footprint, approximately 10.5x11". Finding space to mount it shouldn't be a problem.
Its been a while since I've sold anything on here so I don't have any buyer/seller ratings but you should be able to find some feedback on me with a search. Pm me if you are interested and we can discuss the details including price, which will be well within, or I should say well below, your budget!