I have designed this stuff from the power supply forward, I mean every part of it, and I used to really like the Kenwood stuff for cheap stereo crap. Lately, meaning with the 7201 era, they have lightened things up and used a fan instead of a bigger heat sink. That sucks. A cheap fan will fail and when it does the whole amp will fail. The older Kenwoods had more metal in them, better transistors, more robust power supplies, you name it. The new stuff is crap. I'll sell you my new 7201 for fifty bucks. It functions perfectly, but I want a more robust amp. I will put that thing on the bench this winter to see what it actually puts out, but it's supposed to supply 280watts rms per channel @ 2 ohm at very low distortion. I don't believe it. I had a four x 25 watt old kenwood powering 2 of the same speakers and a sub last year and it was louder and cleaner. A lot louder. That amp is in my truck now. A fan will not remove heat as uniformly as a big ass giant heat sink, so the devices cooled will not have a uniform temperature, and will not perform uniformly.
I would build my own amps but the hard part is making a pulse width modulated switching power supply that is small and quiet and supplies gobs of power. I made some good ones but they roached on the board when something got unstable. I gave up after a while The power supply is absolutely the key to good amp design, its why some amps will supply 4x times the power into 1/4 the load and others won't. The amp side is easy, just use big, high quality, relatively fast transistors and not a lot of them. Fewer components means less distortion.
I have had great luck with Hifonics amps. El Cheapo, made in China and they have that boy racer stylin' with the blue LEDS and stuff. They are heavy, which is the first sign of quality in any electronics product, no shit. Big heat sinks, power supply coils, big caps, heavy parts. If you open them up, they have high quality transistors, big, crudely machined heat sinks on every one, big ass wire, big caps, everything. They are ugly but they work. I will put mine on the bench this winter and put it through the paces. I tested it briefly before I installed it it met output specs no problem. Distortion analysis over 20 to 20 khz is another thing, that takes a while to determine. I have no issues with their stuff so far, reliability wise. I have 300 watts @ 2 ohms going to my sub, I may try a different amp to see if I can put more watts to that thing, it is a JL. I want to add another sub anyway.
The amp stuff is easy, as long as they don't cut corners. The key is weight. It sounds stupid but it's the truth. Weight is expensive.
