Obviously you do not want to record empty tracks (thus causing unneccessary load). So whatever channels you record, they get counted in a consecutive, gapless way. Upon playback you have to assign those channels to the same outputs, IF you have the need to do so. Usually for most applications this is not the case. Your description sounds more like you expect a typical multitrack recorder, and this is not the idea behind DURec.

You assign the playback channels in the TM FX, these are saved then within the Workspace. So something like recording a show and doing virtual soundchecks later is zero problem. You just have to set it up once correctly, save the Workspace and reload it whenever needed.

Of course you can assign the playback channels in stand-alone mode via the display as well. Check Channels, Analog Out 1/2, Settings, scroll down to Play Channel. Now turn encoder 1 to quickly set up all other DUrec playback assignments.