Another off the wall DCC vs. DC question

[cacole]

You cannot put a sound only DCC system in a locomotive and have it work on a DC layout. A DCC sound system works only on DCC, because you have to have a DCC signal to activate the sounds by pushing function keys, which you don't have with a DC controller.

[dragenrider]

Thanks, cjcrescent. What I'm trying to ask is if the DCC sound decoders can be run simultaneously with DC, even if they are not made for DC. In other words, can you run the signals for both through the track at the same time?

[cjcrescent]

Currently the only sound available that works on both DC/DCC is QSI's system. This currently is in all BLI locomotives, Lionels just discontinued locos and the new Athearn Challenger and I think will be available in a few locos from P2K and Atlas.
Somebody correct me if I'm wrong, please.

[dragenrider]

I understand that DCC sound only decoders are available. But, can they be used on a DC track layout and/or in a DC engine? If they receive their input via the rails, would the DC throttle interfere? How about being parked in a block with the switch off? How would they receive the signals and needed power? [?]