no digital sound from USB and Univ.port on TX-NR509

I was getting digital playback from USB front port (using iphone)initially... now only analog. I have pressed the Mode button on controller as instructed by front display and this worked for a few occasions. Now it doesn't. I purchased the Onkyo dock hoping to circumvent the front USB and after a few minutes of play this went Analog as well. I am very pleased with my NR509 except for this drawback... Any suggestions...

Boricuarx7,

I'm curious as to how you determined there was a digital signal coming out of the USB using an iPhone? It is not able to actually do that as USB is defaulted to an analog signal and can not be up converted to digital.
I ran a test in our lab just to be sure also.

thanks for your response. I was in fact, at first, able to get "digital" upon depressing Mode button on controller as requested by front panel display: and it would describe "digital" soon-after pressing Mode. Then after a few uses (from iphone 3)I could not get "digital" again. That when I decided to purchase the Onkyo dock for use of rear Universal port...even when Mode button is pressed I still can't get digital playback...even with other ipods. All buttons on controller work when iphone is connected; just no digital.