Hardware Recorder vs Software Recorder

???????????? Maybe I missed something. No disrespect ... The tracks are save to the hard drive on my PC via Reaper. The 1640i is the input (recording) and output (playback/mixing) interface. I have a compressor for the 2 channel mixed output interfaced with the Tascam cd-rw900sl recorder. I have a another compressor for my vox tracks and a lexi ms200 on aux sends/returns. One song, for example is comprised of 12 tracks. I mix the 12 tracks on the 1640i down to the tascam, get a good balance (or perceived balance) then burn that mix version to a cd via the tascam. I would like to accomplish the same, mix 12 track to stereo inside the DAW. I can accomplish this in what way(?)without routing the tascam back to mixer input to ch15 andch16 and recording to the DAW as stereo. How do I route the 1640i output channels back to Reaper to record the mix as stereo track, take advantage of the output compressor, lexi and Reaper FX package? Am I Half Baked or just confused? not sure myself ..

I went back to the Reaper User Guide to read further ...