OK, here is the deal on D class amps.
Most amps are class AB, the signal is very clean but they are not very effecient, usually around 50-60% the rest goes up in heat.
Class D amps are very effecient usually around 70-75%, but they are not as clean as AB amps.
The difference in signal quality is very small though: AB .0005% D .005%
Class D JL amps also only are designed to work only from 20-500 hz, which is fine for subs.
JL Audio makes very good product and even though I don't carry the product, I got one of the amps from a jl dealer and put it in a customers car, pretty impressive.
I work at Mobile Electronics in N. Arlington, 2274 N. Collins 817-265-1298 I will be here on Sat. from 9-5
[This message has been edited by 89lx5.0 (edited 06-28-2001).]