Actually, I'm looking at them, you did make a very good suggestion. For now, I haven't seen any splitter that supports my purpose, but I'm still looking around.
And yes, it only splits channel without any form of processing, but by saying "handling", I mean whether it can run or not. For example, trying to passthrough 5.1 content over a usb to optical which only supports up to 2.0, it certainly won't work. The same happens when you try to passthrough/split-channel DTS content on Dolby-only splitter. That's what I meant.