To me, the emulated sid on that thing sounded quite agreeable to my ears at least. I'd need a closer side-by side comparison of those versus the two different varieties of real SID chips to tell the difference, I suspect for now. I've listened to a few 6581 vs 8580 comparisons now, and the main difference seems to be the latter chip sounds like the signal's being passed through a low band pass filter, which pretty much kills any spiky pwm speech and things like that, although tunes that are designed for the 8580 can have killer basslines that the 6581 can't reproduce well at all. And I've found this video which switches between the two real chips and the U64s emulation on the fly, which is fairly revealing: Code: https://www.youtube.com/watch?v=gFSnjFtgwUI Seems the emulator is sounding more like the 6581 in a lot of respects, especially when compared to the 8580. And it's a known quantity, but if your musicing is more in the vain of trance or funk then you'd have to go a way to beat a real 8580.