Reply to Using The S4 In Combination With An External Mixer

Ok, so I've got a question and I'm hoping to hear from people that have used this type of setup. :

I currently use an S4 with 1200s and timecode control along with a Pioneer RMX1000. I've been contemplating switching to an Allen & Heath Xone 22 for the longer volume faders, filters, mic input and FX send/return.

I love the S4, but I can't use the mic input with timecode, and I can't hear the RMX1000 effects in my headphones. I'm believeing I can use the S4 to handle just about everything besides the mixer, and use the internal sound card to send deck A through the master out, and deck b through the monitor output, sending them to the xone 22. I've never read or heard about anyone doing this, but I'd like to find out if this is a viable solution to my needs. Any info would be appreciated. Thanks.