Cool thread guys, I saw reference to Yamaha stuff so wanted to tell you guys I have one of these boxes "The Amiga Project XG"
Eh. Unfortunately, by the time Yamaha developed their XG standard, they'd gone entirely into ROMpler territory, playing the same sets of samples from ROM (downsampled to lower rates on the cheaper instruments) on basically everything, sacrificing pretty much any potential for sound
creation in the name of "realism." Bleah. Their FM synths (or even their ROMpler/FM hybrid synths like the SY77) were much more interesting.
Amiga can do pretty nice sounding SID renditions (Per Hakan Sundell's C64 Demo for Amiga OCS and his SIDPlay app sound excellent...he also wrote C64S DOS emulator).
The renditions I've heard on the Amiga are
nice in the sense that they sound good, but they're only kind of reminiscent of the SID, and nothing you'd ever mistake for the real deal. Then again, I haven't kept up on the Amiga side of SID emulation for a while...
The problem with having a traditional soundchip is they have a distinct sound.
Whether that's a problem or not largely depends on what you want out of an audio device. If you want flawless reproduction of a pre-defined sound, then yeah, you're not going to want a synthesizer chip - what you'd want is the highest-quality DAC/aliasing filter combo you can get and enough memory to store a good recording of the sound. But for those of us who want an
instrument, that's a silly complaint to make. You wouldn't gripe if you bought an acoustic piano and found that it was incapable of sounding like a Hammond organ; that would be silly. The AY chips didn't suck because they had a distinct character, they sucked because they were capable of exactly two kinds of sound (square waves and noise,) and there's just only so much you can
do with that. Whereas the SID is much more capable, but still distinctive and full of character.
Having said that SID is a genuine analogue synth on a chip and that is the key to why it is such an awesome piece of kit to design things for. If you look how much 1980 mono synths with similar technology cost you will not call a $20 6581 chip over priced ever again IMO 
Well, I wouldn't stack the SID up against higher-priced monosynths - it doesn't get quite the full organic, analog feel because its oscillators are digital, the ring mod and oscillator sync are rather lackluster, and the filter resonance doesn't even get close to self-oscillation. (Though it has its own advantages - there's surprisingly few synths that can do PWM with a center point other than pure square, or provide anything like the noise + pulse combo waveform. It'd certainly be a lot closer contest against single-oscillator budget monosynths like the SH-101, where it could compete on sound
and deliver polyphony.) But yeah, it is pretty dang incredible how much Bob Yannes delivered in one little chip for a low-cost home computer
Biggest problem with SIDs IMO are that no two even from the same revision sound exactly the same ie two 6581 revision 3 chips may sound different even in the same machine...a subtle difference but with games that use complex filtering effects it can be noticeably different.
Au contraire, that's part of the beauty of analog gear
Not the same sound, BETTER sound using any old Win XP laptop costing $50 and a copy XMPlay. The only unusual thing about my setup is it's sitting in my home cinema and the music is sent digitally to the amp so it is the purest possible sound of what the MOD is supposed to sound like before the cheap ass components on the A500 motherboard destroy the quality even more.
All depends on what you define as "better." A lot of us
like that sound, however much it might make audio snobs shudder.
That means there's more than plain D/A and standard analog filter. So could anyone describe what's special in technical terms?
"More than" a DAC and filter, no. But again, even a system with just a DAC and filter can have its own distinct character, because those components color the sound in their own ways. No electronic component, especially no
analogue electronic component, is actually a mathematically ideal implementation of its nominal function. As has been noted, the Amiga's DACs aren't even close to linear - that's going to distort the output. Also, samples are fed in at varying rates and played back without interpolation, which means that any aliasing noise is going to come out at a different frequency, likely well within the range of human hearing, which is also going to color the sound.
And finally, there is not a single analog filter in existence that has a mathematically ideal, linear frequency roll-off. (Which virtually every emulator in existence gets wrong; even reSID was wrongly doing linear roll-off until very recently.) Even the cleaner filters have a curved roll-off, and a lot of them will have different ranges roll off at
different curves. Additionally, real-world filters don't just attenuate frequency components, they change their phase relationships. All of this varies
wildly from filter to filter, with the result that just about every design is at least subtly different. (A good place to go for further reading on this subject would be installments
4 and
5 of Gordon Reid's excellent
Synth Secrets series for
Sound on Sound. The man knows his stuff.)
So, really, even with a very simple DAC + filter system, there's any number of factors that can give a distinct character to the sound. It's probably not impossible to emulate them properly, but I don't know of an emulator that
does. Many get things basically right, but I'm not surprised that folks like magnetic feel that only the real deal provides the same sound. It's complex.
