That's why I'm interested to see why in the hell he would want 4300 watts at less than 70% efficiency. That's fucktarded. You do realize that most modern Class-D amplifiers are 85-90% efficient right? Please don't tell me they have too much THD, that's a worthless measurement. Nope just Don't like the way they sound. As Steve will tell you it took him Many years to figure out how to make them not sound "flat". There is a World of difference. I can take a new Class D that is 1200-1500 watts replace it with a Series VIII Zues ot a Autotek 7600 and it will sound better and hit harder. I can deal with the power consumption. I don't need to anything near 4300 so it wouldn't ever get run that low. Shit the heat that Class D put's out at 1 or 1/2 ohm is more than the Zues at 4ohm's. My 2 cents I have tried everything over the years I have been doing this since 91-92 and haven't stopped once so believe me I have heard and tried alot of stuff over the years. If there wasn't that much difference the demand wouldn't be so high for Old School Quality Class A/B amps. Most people can't hear the difference between 1% THD and 2% THD.... So everything below 0.5% THD is good enough, and if you set the gain low enough you get less power and less THD. Test a class D amp at 4 ohms or test a A or B class amp at 1 ohm, let's see which one will get hotter. It's normal if you lower the impedance, the efficiency drops= more heat. Don't think you could hear a difference between different sub amps, i know that (good) highs souns different with different brands of amps. But it's a really nice amp really powerfull amp certain at the time it was made.