I'd say yes, to fully appreciate Dark Knight Rises, definitely go see Dark Knight first. In fact, go see Batman Begins if you haven't, to fully appreciate the movie because it makes references to all two prequels.
I was a little disappointed in either the sound mix, or the IMAX sound system here in Sydney which is labelled as the 'biggest IMAX in the world'. I got crisper sound from the speaker system at home watching The Dark Knight; but of course, everything would've been remastered for the Blu-Ray/DVD. It just seemed as though a few juicy pieces lay in the dialogue which is muffled at times (re: Batman and Bale).
I might give it another go in a regular cinema and see how that ends up - if anything, just to experience the film again. It raised some goosebumps in me, that's for sure.