Ruby amp conundrum!

[craftyjam]

Hello, new here. I've got a ruby amp on my breadboard according to the schematic. It works well and good when i don't include the output coupling capacitor, but then the chip overheats. However, when I include an output coupling capacitor of any value (I've tried from 47uf to 220uf), the amp sounds all scratchy and bad. I'm waiting on some heat sinks for the chip to disspate some of the heat, but I would much rather find a way to include the output cap and still have the amp sound good. I'm using two 3 inch speakers in series for a total of 8ohms. I've tried all manner of things to treat the noise.
-Zobel Network
-470 uf decoupling cap close to the chip as possible in paralell with 100nf cap
-100 nf cap from pin 7 to ground.
-Pins 1 and 8 disconnected for lowest possible gain

Any ideas on why this output cap is giving me trouble? Thanks in advance.

[swamphorn]

The LM386 seems to be very sensitive to supply bypassing but it seems like you've tried bypassing to the fullest extent. I've had problems with LM386s misbehaving for no logical reason myself. Where did you get your '386s from, and what is the manufacturer marking on the chip? I suspect there is a problem with counterfeit or out-of-spec '386s on the market.

[craftyjam]

The markings on the chip are: LM386N H820CA
Impulse buy on ebay. They were so cheap I couldn't resist.
Thanks for responding!