Does the USB port only function as a stereo audio device for the PC, or can it pass encoded DD/DTS from DVD player software on the PC?

Some USB audio devices on the market can do this, so I'm wondering how it was implemented on the 990.

It's useful for some folks if it's just stereo, but it would be a very slick way to handle HTPC audio if it does support passing encoded DD/DTS from the USB interface straight into the surround decoder engine.

This is an interesting question, and I don't think we've seen enough to tell either way. I glanced at the Sherwood manual to see what it does, and it only supports PCM. We'll have to wait a bit to see if the 990 retains this limitation.

My guess is that if the Sherwood only supports PCM, the 990 will only support PCM. Still, it's possible they implemented it a bit differently.

Depending on how the hardware is architected, it's possible they could do this as a firmware update in the future. If the USB interface is tightly coupled to the DSP engine, it might be possible to improve the firmware for the USB audio device and have it pass DD/DTS into the DSP. If they used an off-the-shelf USB audio chip and glued it to the DSP engine, this will be more difficult. I don't see this as the likely implementation, though, since the USB interface can also be used as a means to update the firmware. Chances are, it's done as either a USB transceiver attached to their main processor or DSP, or as a generic USB microcontroller with some interface to their processor or DSP.

Enough geeky rambling for now.

Cool geeky rambling, though (speaking as an engineering geek). Glad to see you hanging around the forum again, Prefect.

It only passes stereo via USB. I am testing out tonight though. I want to make sure it can decode AAC (itunes).

Shawn

Thanks for confirming that. Kind of a bummer, as it would not have been a huge deal to implement, and would have been great for HTPC users.

As far as decoding AAC, that is actually independent of the USB audio device. The PC still handles the decoding and sends raw PCM over USB to the codec, as if it were any other sound card. It should work just fine with WAV, FLAC, AAC, MP3, WMA, etc.