Hi Paul, good question about the case, I got a "look" yesterday when the new addition to the stereo was revealed

I hadn't thought about it much but now that you ask I do have a case in the workshop that's about the right size. Someone on the miniDSP forum gutted an old DVD player or something for it.
Advantages of the 2x8: you don't have to switch the USB connection to adjust the other channel. Even better, you can link left and right channels so you don't have to make the same adjustment twice. A big convenience factor there. 96k internal processing, so high-res is open to me now to explore. Balanced ins and outs, which can be useful. I would recommend getting the digital card. Lots to explore there still, e.g. upsampling on the computer w/ dithering volume control and/or the inbuilt digital volume.
I'm still exploring but so far I think soundwise it's a nice improvement. I can't say if it's the 2x8 board itself or the digital I/O as I changed both at the same time... I'm getting a
small amount of noise but most of it's from the amps - the curse of using efficient drivers!