BDA-1 has a pair of 24-bit Crystal CS4398 DACs, one per channel in a dual-differential configuration
BDA-2 uses 32-bit AKM 4399s, adding support for asynchronous USB (up to 192k)
BDA-3 uses 32-bit AKM 4490s, adding support for DSD up to DSD256 (ie. quad rate DSD) up to 11.2MHz
SP-3 has the same DACs as the BDA-1
So I would expect that the "D to A" in the BDA-2 and BDA-3 will be "better" and "a lot better" respectively than the SP-3. but there would be little to choose between the SP-3 and BDA-1.
Of course the quality of the pre-amp will also be critical, and the one in the SP-3 is superb, so it's not simply a shoot-out between DACs...
...and there's the wider cost-benefit to consider; not only does the SP-3 have great DACs and great pre-amplication, but it's also multi-channel which therefore means multiple DACs and lots of digital processing too.
Personally, I went for the SP-3 as the heart of my system, including the provision of the D to A capability, and it's worked-out brilliantly. I've heard or owned units from most of the top performers - Classe, Theta, Meridian, Lexicon - and I've yet to hear anything that comes close to the Bryston SP-3.
Ian
