Oh believe me, it's very bad.
If you have a fast PC, try out VICE with reSID emulation turned on, and you will see... The filters sound like tin-can on CCS64.
If you havent used a commie in a loong time, and if you are not much of an audiophile (I Am , and very picky
) you might not remember how good sounds is. At first I though CCS64's sound was the bomb, then I tried the reSID engine in SIDPlay and was bombed away.
Go ahead, download SIDPlay, your fave tunes, and listen to them with the normal engine. The nswitch to reSID and you will hear the difference. Is very noticeable
try the Giana Sisters tune, for example. The more filters used, the better the results.