The RR2150's USB input allows the receiver to serve as a sort of "external sound card" for a computer. I doubt it would work with any iPod docks.

When using an Ipod as source, consider the overall signal path. Are you playing lossless files? If so, a dock with a good internal DAC or a dock with a digital output and a separate DAC might be worthwhile, but most docks have analog outputs and many of those use the iPod's internal DAC as well. If you are playing anything with lossy compression, spending a ton of money on the signal path may be kind of wasteful.

I've had pretty good results hooking an iPhone or iPad to the RR2150's auxiliary input. I did it knowing that I was playing a lossy source (albeit at a pretty good bit rate), so I didn't expect the same sound quality I'd get from a CD or SACD through the BDP-83SE, but it was still pretty pleasant.