I bought this player 3 months ago, and from day one experienced loud whirring noise on random blu ray discs. This did not happen with DVDs or CDs.
I assumed this would be rectified by a firmware update, I finally got round to getting a 8m Ethernet cable and did the update. No better. In fact I've had 3 discs rendered unwatchable due to the loud noise, since the update.
So I got in touch with Superfi and also spoke to Denon. Denon denied knowledge of this problem, although there is mention of it on other forums. Probably caused by the different spin rates of BDs. So it's going back on Friday. They'll probably check it and send it back unaltered, but I've given them some title names so hopefully they'll try it with those.
Now using my Sony S570 from the lounge. In terms of PQ (and CD SQ) its noticeably not as good, but the wireless and Smart functions make up for this.
Ill never spend so much on a BDP again, it cost me 450, but the original 750 is taking the ****. The more you spend the less you get.