Power Amp modules for sub-woofer amp

Anyone knows about good Power Amp modules on sale to build a decent sub-woofer amp? They must be (very) good for 20 to 50Hz. No power supply or x-over needed, just the amp modules. Regards
Velleman has kit amps that are bridgeable. Their power supplies are sold separately. Madisound and others have sub amps that are ready to mount into the enlosure. These have crossovers, power supplies...ready to bolt-in.
the reason you won't find FTC power figures on any in-speaker amp is because the FTC does not require it. Please I dare anyone to find a more incorrect place to mount an amp than inside a woofer enclosure? Do you think the money people spend for resonance control on the most expensive stuff out there is for nothing? Wrong if you said yes. have you noticed all the failed built-in sW amps? I wonder if heat, enclosed spaces & vibration are good for heat-generating electronics? Try the Marantz MA-6100, brand new model, I just sold two ($300 list ea) & they sounded as good up to 450 hz as my extremely nice custom amps. 180WRMS real power (not the dynamic music power crap) into 4-ohms. I discount of course.