I have to agree with Tahoe, even the Atari Falcon had a DSP built-in around that time ~1993. The only thing the A4000 has going for it is the smaller form factor and the AA chipset. Other than that the A3000 is a better machine. You can tell by the prices they are fetching right now on eBay. The marketplace hath spoken and declared a winner.
Doomy is wrong about the 2000 though. Nice machine for it's day (I'm typing this on one right now), but it's no 3000/4000.
