Thank you for pointing out the obvious.
Obviously a guitar amp is not the best medium to amplify a mix with drums, bass, etc. but as I said it can be used while practicing over backing tracks. It appears I am not the only person thinking this way, since a lot of amps appear to have this feature these days. For an example the Balckstar HT-5 comes to mind.
In relation to the fact that the L6 link is a digital connection and the cd/mp3 input is analogue, so is the guitar input, which means that there is already an a/d converter inside of the pod. The only reasoning I can see here is to save the cost of an aditional a/d converter.
Anyway, for whatever reasons this was the design decision from Line 6 and that is fine. I am just wonderinf what, if any, is the best workaround for it?