You have to look at this:
http://cgi.ebay.com/KLH-KL-2400-2-Channel-Stereo-Tuner-Receiver_W0QQitemZ260549940018QQcmdZViewItemQQptZReceivers_Tuners?hash=item3ca9fc9332I have one of these beasts and it's remarkable! The preamp isn't that good, BUT- it has jumpers for amp in and pre-out!

The amp is very,very good. It uses a 300VA toroid. The circuit is a basic push-pull, sturdy reliable one rated for 100 watts/channel. I went inside and disconnected the front panel controls so the display remains black. (Easy to do- just unplug it.)
The anodized solid aluminum face plate & knobs are nifty for such a cheap thing. It's something to try and awesome for under $50.00. The amp is very efficient too. It has a respons eof 20-20,000hz and a THD rating of something like .01%.
Known issues: Sometimes the speaker protection relay needs replacing/burnishing on this model.
NOTE: Unlike most cheap receivers, this one has a removable bottom access plate! It's built quite nicely.