There is a very interesting Class D subwoofer amp with an integrated 220V SMPS,
designed by the Russian DIYer, Sergey Lebedev. He can supply
PCBs, kits etc, but not sure about customs issues etc. It uses fairly easy to wind
toroidal transformer/inductors and he has very good instructions on his site (via google translate).
http://darkamp.ru/usilitel-dlya-sabvufera-300vt/
https://vk.com/darkamp
http://darkamp.ru/kontakty/
Characteristics:
- power: 340 watts (before the clip, 80Hz 4 ohms);
- load resistance 4-8 ohms;
- power supply 220v;
- frequency range: from 5Hz to 80-180Hz (depending on the position of the LPF knob);
- adjustments: volume and low pass filter (80-180Hz)
- sensitivity: 0.5v;
- protection: power supply and amplifier from short circuit, protection of the subwoofer from constant voltage at the output of the amplifier;
- dimensions L * W * H: 204 * 195 * 54mm;
- weight: 2kg.
Technical details of on board SMPS: MOSFET switches 20N50 (20A, 500v, 0.25ohm), PWM SG3525, frequency 50kHz.
Amplifier: switches 40A, 200v, 65mOhm, operating frequency 130kHz, preamplifier filter NE5532.