Sounds like the amplifier chip out of a Sony surround amplifier?.
I'll check at work on Wednesday (I'm not back till then), but many of these hybrid chips are no longer available - unless you can find them surplus from somewhere?.
NTE ( the replacement semiconductor people ) carry it as NTE1817, if you can't get an original from Sanyo. NTE have a pretty good supplier base, many of the larger distributers carry their line.
Here is the NTE ditributer page:
**broken link removed**
It is about $30 Canandian, noit sure how much in your area. Sanyo used to be pretty good about selling parts to consumers, if you could get to one of their repair centres.