AB will "technically" sound better (although the difference is somewhat negligible for most people). these amps are a lot harder to find and i'm pretty sure they'll be a lot more expensive and prob won't have as much power rating to them. i would totally take an AB over D but cost vs return really becomes a key part in this.

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Setup:
Panasonic CQ-C7301U HU
Infinity 6.5" fronts
Infinity 6x9 rears
Infinity Reference 12" Subs
Clarion DPX1800 900W Amp
Hardwired IPod
Escort X50 Radar Detector (blue)

Waiting To Be Installed:
Kenwood KAC-8452 4ch amp