The original PlaySID (as far as I know/remember) didn't emulate the SID filters, and tunes which use sampled sounds were modified to be able to play more effiently on the (68000) Amiga.
There are various other SID players on Aminet:
http://aminet.net/search?query=sidp
Ones which emulate filters will have higher system requirements than the good old PlaySID. But they'll probably sound better, if your system is fast enough to run them.