Wade through every RadioShack you can find! These cool little amps are rated at 50 watts, used to be $160 to $300 depending on when you were looking but now, they are $15 because they are totally useless without some silly ass sending unit you need to make them work as designed. The sending unit is no longer available...
So, just pop the top, remove the silly receiving board by disconnecting some cables and you end up with a very nice, smooth sounding little amplifier complete with nice torroid power supply. (just feed the signal into the "Line Out" jacks after disconnecting this board). Don't poke around in this one with power applied!
I auditioned it on a friends KEF bookshelf speakers and it sounds very sweet! I'm already looking to see what hopups could be done to it!