Francis_Vaughan said:The G4 iPod uses the PP 5020 which has the capability of being a USB host (something that is used in the iPod photo to allow it to download files from a camera.) There is no intrinsic reason why any G4 (photo or ordinary) iPod could not become a USB host and deliver digital sound to a generic USB sound output device via the dock connector. That it can't is simply a marketing choice by Apple. (As is preventing a non-photo G$ iPod downloading files from a camera.) It may be that they are acceding to pressure from the recording industry to make it hard to get digital audio out of the device without and DRM tags. Curious really since any Apple computer will do it, and indeed an Airport express will as well.
This is my single biggest beef with the iPod. There is no sensible reason why it should not be able to deliver output to a USB sound device.
Francis_Vaughan said:Actually it is not hard to do this at all. The adaptor plug exists - it is the camera adaptor Apple sells to allow you to connect the iPod to a camera - all it contains is a set of wires from the dock connector to the USB host plug, and a resistor that tells the iPod that this particular connector is attached. iPod dock plugs are actually dirt cheap. (I got 10 for $20.)
So, Apple have a plug, they have host driver code (for the camera download). It would be trivial to stuff the digital stream down the USB instead of the I2C.
As to the device you connect it to. How about a Headroom Bithead? Or for home use a large number of the other new Headroom headphone amps. Or you could connect it to the original version of the Harmon Kardon Sound Sticks. Or I could connect it to my M-Audio USB Audiophile, or the legion of new USB based DACs.
For something that simply needs the will to do this lack of functionality really is silly.
And yes, I have high hopes for the iPod Linux guys. I'm waiting for a stable build for the G4, then I might be tempted to simply migrate, almost as a protest. Unfortunately Portal Player make no internal documentation available, so everything is painfully reverse engineered - no small feat - and they have no USB support at all currently.