I am almost certain that with the current version of Asset it's not possible, but just in case I missed something in the documentation and forum, here's my problem:
I have 5.1 DVD Audio rips in FLAC; most of them are 94/24. I have two players - Marantz NR1602 and Oppo BDP-93. Marantz plays Hi-Res stereo FLAC (96/24) just fine and up to 48/16 stereo LPCM, but cannot handle any multichannel streams, Oppo can handle Hi-Res multichannel FLAC. What I ideally want is the device specific re-encoding that would serve 5.1 FLAC as stereo FLAC with the same bit depth and sampling rate (that is, FLAC 96/26 5.1 downmixed to FLAC 96/24 stereo) to Marantz and any FLAC as is to Oppo.
Alternatively, if it were possible to hide some folders/containers from a specific device, I could simply have two versions of the albums - one for each device.