Building amplifiers

i am currently setting my self up a task of building my own subwoofer or 2.1 channel amplifier for my computer room.
i might be going for 300 watt toroid transformer for the tda7294 2.1 channel 80 watt x2 plus 160 watt subwoofer amplifier.
with 1 pc aluminium heat sink.,.

Basic parameters:

Power Supply: AC Dual 18-28V

Size: 218x98MM （L*W）


Power: 80W X 2 +160W Subwoofer

subwoofer is made with BTL 2pcs TDA7294

Potentiometer features: low frequency adjustment, subwoofer volume. Left and right channel volume, treble, bass
　

interesting enough is that it is really cheap!

and thats why im going for it.

dont know what to do once ive finished it.

might run some speakers obviously