I've been working on a lightweight class D bass guitar amplifier. I originally started with the D2 Audio chipset now sold by Intersil.
I found that there was practically no support. Even though I was an FAE at Intersil, I couldn't find any documentation and most of the folks that worked on those parts had been laid off. The D2 parts were great. they had 12 output drivers per chip with a DSP pool, but it would be impossible to actually make a product with them.
Looking around, I found a bunch of parts at TI. I don't know if these came from National or TI originally, but there's a bunch of parts available at different power levels. The all seem to have integrated power stages. I chose the TAS5630. It has an analog input and will drive 300 watts into each of two channels. I ordered samples and started to collect parts to build an initial prototype, but I found complete amplifiers...