This is my latest project, and it has taken a much longer time than it should have. It is the Symmetrical MOSFET amplifier designed by Anthony Holton of www.aussieamplifiers.com. A three-stage, Class AB amplifier, it can deliver somewhere above 200W into 8 ohms and 400W into 4 ohms. The problems I have had getting this project up and running are almost too long to list, and most have been because of my own stupidity. In short, one channel of my amplifier is almost completely dead because of problems with the output stage (and it's awaiting replacement parts). The other channel is working, but I had a close call with it... I connected the speaker negative lead to a spot on the PCB that looked like the right place, but it had a 10 ohm 0.6W resistor between it and ground. That resistor went up in smoke, quite literally. Luckily, replacing the resistor and connecting the output directly to ground solved the problem. This channel has a bit of uneven bias: readings across the source resistors in the output stage are between 0.014-0.020 volts, indicating between 64 and 91 mA of bias per Mosfet. But that doesn't get in the way of operation. The power supply varies between +/-73-77V based on line conditions, it consists of a 750VA 50V Plitron toroid, 400V 35A bridge and a pair of 23,400uf capacitors (per channel). DC offset is between 6-8 millivolts and there is no turn on thump. With this amount of bias the output into 4 ohms should be Class A for the first 3 watts or so... I may try to increase the bias later since I have the power and heatsink to handle it. This project cost around $400 for a pair of monoblocks built with quality parts: IRF Mosfets, polypropylene and polyester capacitors, etc... and overkill power supplies and heatsinks. With any luck it should have sound quality up there with very good quality high power Class AB amplifiers. As soon as I have two channels , I'll post my impressions of the sound and compare it to my old amplifier as well as the Class A Zen amp. I just tested this thing hooked up to a single Kit281 (87db/2v) a bit, slowly increasing the volume until my voltmeter (which has significant lack of high frequency response) was reading between 8-12V AC. This means somewhere around 10-30 watts continuous and 90-95db at my seat. The sound was not harsh or "loud", still detailed and has a much more dynamic, stronger sound than I've had before...at least as far as I can tell at this point. And yes, it will go much louder. A simple calculation tells me that 75V rails should be good for peaks of around 550W, although its ability to hold that power continuously is questionable. At this point it doesn't really matter; I was just looking to squeeze whatever dynamic capability I could out of these speakers, which had better not require 500 watts. I didn't try to turn it up more because I am concerned with the thermal coupling between Q10 (the Vbe multiplier) and output stage Mosfets... at the moment it is superglued on top of one of the IRFP240s, with a dab of silver thermal paste in the middle. You don't want to know what happened to the amplifier where the Vbe multiplier was on a separate heatsink... I strongly suggest those looking for a high power solid state amp consider this design. It has serious power, is turning out to sound really good so far, and the designer has been very helpful in responding to my silly questions. Holton also offers a PCB for a similar design with 800 watts into 4 ohms, which would be a very nice subwoofer amplifier. Thanks for listening.