Not with those headphones, no, but if you were to change to a set of wireless headphones you could plug the transmitter into the SB/FH pre-outs and select the Multi CH Stereo mode when you wanted to listen through them. Otherwise, with a higher level model, you would connect them to the Zone 2 pre-outs and select Zone 2.
Ah . ... misunderstood ... you meant a Zone 2 AVR. The Denon X2000 is a 7CH or 5.1/Zone 2 unit and would be a very nice upgrade to your 591 as it uses the more advanced Audyssey MultEQ XT and has Zone 2 pre-outs.