In terms of 96K benefit, most of it occurs at A to D when you move the Nyquist further away from audio and employ a gentler filter. Therefore, you can convert said recording to 48K (or from 88.2 to 44.1), mix in and master in 44.1 or 48 with your DA7 (using sample converters like Z systems or DCS to feed the ins) and still derive a slight, but audible benefit. I agree with Restes that once you're in digital, mastering at 96K from a 48K source is a waste of time and resources, however.