I've seen some statements that refer to the 3310 having the Burr Brown DACs. But nothing on Denon's site appears to support that.
It's not confirmed in any way... what you have read/heard was just speculative based on similar logic to what you had (e.g. "it has BB ADC's, so it seems logical it also has BB DAC's).
A couple of notes on your (very thorough and accurate) comparison list:
- 21367 x 2 32-bit Floating Point instead of x 1. I'm not sure if that directly means anything, but I assume it's part of the reason for things like MultiEQ XT over MultiEQ.
your speculation is correct that this is primarily to enable MultEQ XT, which is only available on receivers which have a specific amount of DSP power to devote to Audyssey processing. If you compare the spec sheets, the 2809 (with MultEQ XT) had dual DSP's, and the 3310 (no XT) has only a single DSP (like 23XX and below).
Audyssey DSX (not even mentioned in the feature comparison
The 4310CI is the first receiver in the world with Audyssey DSX, so I assume the fact it is missing from the spec sheet is simply because Denon's web dude hasn't added that "category" to their online spec database.
It's a good list of extra features, but I'm not sure it's the best use of $500 extra that could be spent elsewhere. If the DACs are lesser though, might that make a big difference in SQ?
Actually, the DAC's would be one of the smallest reasons.... at that level of receiver, you are essentially assured of very high quality, transparent DAC's with a very high S/N ratio. The DAC's are not going to be the limiting factor in sound quality between a $1500 receiver and a $2000 receiver. The other features (especially MultEQ XT vs regular MultEQ) will have a much greater impact on sound quality improvement from 3310 > 4310 than a slightly better DAC...
And, besides, I'm sort of speculating myself -- it's impossible to separate the various reasons why Receiver X will sound slightly better than Receiver Y one step down the chain. I would just chalk them all up as "4310 will probably sound a little better than 3310" as one of your bullet points when deciding if you want to spend the extra money.