seems most owners prefer the hdmi hookup (including myself). i ended up trying and sticking with PS Audio's own I2S-12's. these are solid silver as apposed to the silver plated I2S-10's.. felt they greatly improved detail and soundstage (width and depth). compared them to audioquest, monster and wireworld hdmi's. the I2S-12's sounded so good that i stopped searching soon after trying them. would like to try the signal cables steve mentioned above someday. what you land on will more then likely depend on what you're looking for sound wise. don't think there's a right answer regarding which hdmi is "best".
also found the pwt/pwd to be very sensitive to vibration. a good rack/stand and footers made a huge difference imho. a few of us have also found that power cords made a substantial difference in sound as well. i went with PS audio pc's (ac-5's) but in all honesty, only tried one other pc brand (furutech). regardless.....i'd dump the stock power cords and find something that works for you.
have had my pair for over a year now and still love um. i think they're giant killers when set up right. with the trade in program, i also see the pair as a steal at 4k. lots of bang for buck imho.
cheers