Not necessarily, it only states "Use of the extension cable may cause harmful interference.", it doesn't say it won't work or cause damage, I am thinking by the interference reference meaning RF that might be picked up etc.

Hmmm, that's weird. I would have thought that there were many considerations as to whether or not the files or the folder hierarchy would be recognized, but I didn't think "using a cable" would be one!

Man, that would be something if I could just plug my hard drive into the receiver to access all of my music. I'll have to try the XBox and see if that works....!

Mark, just because the manual says it does not make it true... In fact, it's equally likely to be the opposite. I've got an extra USB drive sitting around, I'll try putting some MP3s on it to see if the Denon can see it. I can't believe a cable would introduce problems... one way to find out.

I just plugged my usb thumb drive into a 10 foot usb extension cable and it played through the denon just fine. I didn't do any comparisons without the cable to see if there was an audible difference though.

Thanks David - saved me the trouble of having to help Mark myself.

Yeah, thanks to everybody for their help on this on!

I'm going to assume that a USB Hard Drive will work!

Yes, thanks from me also. Here's hoping that my Seagate will work!

Odds are that the portable hard drives will work but they will have to be plugged into a power source. I use a HD with my OPPO DVD player and have to plug it into the AC outlet.

Non-expert guess:
It may not be totally a distance thing as RF can be a funny (although predicatble for the experts) animal....
but 10' is not an extravagant distance for a USB cable. I use a couple of this length and do not seem to experience any data issues. If the bits get there OK, the music is not decoded until it gets into the reciever so the more susceptible analogue music signal picking up interference is not a factor.

I don't know enough about USB standards to say for sure.

I suspect this is a "just in case" disclaimer and that using a shorter cable would reduce the odds of any issues and especially if it is carefully routed away from the big power supplies in the Denon.

Also, I have seen music played from a portable hard drive into a 360. My drive and my Buddie's 360. It was plug and play!

Another option would be wireless networking and letting the PC act as the music server. However, because you will have the advantage of a receiver that has fancy, on-screen GUI built in to select the music, you don't really need the PC or the hassle of networking.

That's tech talk for "I will be jealous."

The maximum length of a single USB cable is 16.4 feet (to be smooth as a high-speed, very chatty transport they need to have fast acknowledgements of messages on the bus and propagation delays rapidely becomes an issue). Beyong that, you need to insert hubs (repeaters), which are much more than just cable extensions.

As for power, the bus does not provide THAT much power. Mechanical devices such as harddrives would either drain it all or run out of juice anyway.