Since everyone is interested about the new HU generation, here's a professional review of the most popular new HU's. It's about the following top candidates:
On a scale of 1 to 6 where 1 is best the following was said about Sound Quality: 1. Alpine 1,2 2. Clarion 1,3 3. JVC 1,4 (no time correction) 4. Panasonic 1,4 (no time correction) 5. Pioneer 1,3
note Alpines with the V-drive amplifier internally offer 27 watts x 4, and units using a digital amp tend to have very poor sound quality. It's an inherant drawback to the relatively slow switching speed of the transistors in a D/T class amp. a good class D full range amplifier costs about $2,500 US.