[Another 50 SIDs have arrived!!!!]

The DTV ( http://en.wikipedia.org/wiki/C64_Direct-to-TV) is an emulation of an almost complete C64, including the SID. AFAIK it's based on a FPGA. Take the code for that, put it onto a specialized device, voila. Maybe subtle differences can be found by people who know the proper SID sound by heart. It sounds convincing enough, though (also given the fact that i most often hear it through a crappy but authentic cbm monitor speaker).

Errr,  It doesn't emulate the filters at all??  So it's absolutely not convincing imo.

[Another 50 SIDs have arrived!!!!]

lol.  You'd think they would be more careful after paying some poor sod in a sweat shop a few pence an hour to sand them down and dip them in some double happiness wouldn't you?

It's a shame they don't realise that they'd do alot better if the chips were just left alone, rather than trying

to 'refurbish' them.  So you returned all the 8550R5 chips even though alot of them probably worked ok?  (i can understand why, it just doesn't seem right if they have incorrect markings on them).

[Another 50 SIDs have arrived!!!!]

these chips look very similar to the samples I had from Santion Components. Same font and clear printing. In my case though, they got the date code wrong (8580's in 1984? lol)  And they were actually 6581 chips, with a 100% failure rate.    Still, not as bad as some of the remarked chips going around with 'Commodor' printed on them. lol

In fact, the only company i've ever got 100% genuine New-old stock chips is from Parkeli in Hong Kong.