Any common issues with SNES sound?

[egparadigm]

I have found an auction on eBay selling a SNES which is local to me. The seller has told me that he's not sure if it works properly; specifically, he thinks there was a problem with sound output. He is unable to test the machine as he has no cartridges. Are there any known or common issues effecting sound output?

Also, might I be able to circumvent it by using a Scart cable instead of the bundled RF lead?

It is a PAL, unit, if it makes any difference.

Thanks.