You can get both adaptors, i am using a bnc (adaptor) out of my bdp and rca into my bda. It sounds leet
. could stop by and get another one for the bda in but haven't bothered yet.
I'll echo what cryoparts and wywires already said. Using adapters will really affect the transmission characteristics of a properly built BNC cable. Pretty much ruin the return loss figure. Maybe doing a BNC adapter on a RCA cable isn't that bad since you're not dealing with a true 75 Ohm device to begin with (regardless of what anyone says there is no way to make an interface with true 75 Ohm characteristics over an extended frequency range from a RCA connector - not physically possible), but the other way around is self-defeating.
Fortunately or unfortunately, most digital gear is outfitted with RCA jacks so I guess proper digital transmission seems not to be too important to the industry.
Sorry for the rant, but this has been a real sore point with me for years. The audio industry decided to collectively shoot itself in the foot by deciding RCA connectors were "good enough" for digital, mostly because they were cheap and handy. The effect on signal reflection and jitter is still with us. Some makers stood their ground but they're in the minority. BNCs would not have made the problems go away like magic, but why make the problems worse?
No more soapbox for a while.