The Dual-500,D-500 are both better and worse than a stock 700 series two. The pluses are built in DCP circuit, High frequency destortion attenuator, High / low rail voltage for 2 ohm operation and a built in Cooling fan. The minuses are poor layout of wiring, Way to many output transistors. I have to say owning one , maybe a few more than 1, to me they hasve the following benefits The are rare so having one is they Are unique, have a Few more ponies, not as many as you think, over the 700's. They can be upgraded into a fine amp similar the WOPL conversions talked about here. I will soon finish a full complementary conversion with Joe's control board. Parts are being ordered this weekend to finish, I need hundreds of MJ21195/96's to finish all my projects and just found a low cost national supplier. The first one I converted has excelent distortion and noise numbers compared to the stock unit. Over the next month I will have two converted units to do a shoot out against my WOPL and a very low hour stock Quassi unit and a tuned up stock full complementary unit. I just need to build a proper load back with non inductive resistors. The Audio Precision can hardly wait.