The Tascam and Phonic 18 both do 24bit 96 but have not tried them in RB, to hook 2 Tascams up I have to use ASIO4All that gives 32 in max with a little AD converter on 15/16 but have not had to use that many yet, but two come in handy to have DI tracks also.
RB needs a Record Arm Button above the FX Button for each track, and be able to select the input from a Drop Menu:
Track 1 Mono Input > Tascam 1
Track 2 Mono Input > Tascam 2
or
Track 1 Stereo Input > Tascam 1/2

Might go and throw some more coins in the well.