I had a chance to make it to a few local car audio shops and test some new equipment. Just thought I would give my 2 cents.
I generally ONLY like Class A/B amps for Midrange through Tweeter applications (Anything over ~80hz)
I decided to try the following amps:
JL Audio HD9005, and HD7005
JL Audio 300/4v2 (Class A/B)
Rockford Fosgate Power T600-4
Speakers: Focal 165-KRX2 2-way components ($1200)
Head Unit: Kenwood DNX7180
I also tried misc JBL, Alpine, and any other speakers they had on display at the time (mostly models below $300). All 3 Focal models above $600 sounded similar other than "clarity". No noticeable cutoff or losses in frequency bands, just the $1200 set sounded more "clear"/accurate.
First impressions: All of the Class D amps have no audible noise/hiss when not playing material. Both the Rockford and the JL class A/B amps had audible hiss or noise when not playing material.
The Rockford T600-4 had perceptually more "punch" and loudness, BUT was not more clear and did not have the same full range sound as the other amps. First impression would say its "louder", though it was not gain matched to the other amps so appreciable volume is due to RMS/gain differences.
After 2 hours of listening to various types of music on HD Radio and CD, I determined the Alpine PDX5 and JBL HD9005 "sound" almost exactly the same. Level matched, I would say they would have the same equivalent perceived volume/loudness. Honestly, the only way I could tell which amp was playing was by looking at it. Sound difference was almost not determinable.
Bad camera pics of the demo wall at Car Toys:
Just thought I would post my findings! Let me know if anyone has any similar experiences or reviews!
Edit: Forgot to say, all of the Class D amps had 4 Gauge power connections. The salesman was telling me their installers only use 4 gauge with these amps and have no power demand issues (according to him).