Hi I recently bought THIS amp to REPLACE a Polk Audio 660 4-chan amp I recently bought at BestBuy for $200. A very compact advanced new unit. I posted a review over there about how the Polk had power but SUCKED in sound. HARSH AND SCREECHY AT LOUDER VOULUMES, before distotion set in, but not so noticable at low volume. I checked the site and found out the output transistors are not MOSFET, which is what it says it is, but only the power supply is. I had also bought a second one and returned in a week, just to make sure it wasn't that particular unit. I have Infinity reference kappa speakers which are very sensitive to detail and are 2ohm speakers. I am going to now give you review by comparison of the two. This "Mean Machine" amp at almost HALF the price, SOUNDS ALOT better in mids and highs, It has a smooooth wet sonic caracter, no harshness at all like the Polk amp. And also is a little bit more louder, as I am able to go up 4notches on my volume with clarity. It is also very close in compact size and much more beautiful. Also the terminals are biger and better. Also the filter controls are more effective and linear to adjust for proper balance. This amp performs and looks/sounds/performs like a $300-400 amd and is the best deal amp I ever bought. I was going to get the slightly more expensive MBQuart 4-channel, BUT when I opened the Polk, it looked alot inside like in the MBQuart video, and I wanted to get away from that design, but I may get it in future anyway for my subs, and to compare. I dont care about compact size since this model is mayby inch more all around. So I would easily recommend this amp to anyone looking for a four channel, This "MM" model seemed newer, and the video about the matching output mosfets part sold me. but I would not go lower in model/wattage for loudness.