Stereo track with one left and right or mixed to one mono track?

best regards
Knut

I know this is a super old thread here but I wanted to add my findings for the next guy looking for this info. There is a great reason to do this blend/sum trick in Totalmix FX before you hit your DAW by committing to, lets say, a ribbon mic and a SM57 mic to one clean guitar track in your DAW. This is what the Steven Stevens MOD is which is on the back (blend) of the BAE 1073mp dual preamp (analog) only you're doing it thru TotalMix, digitally. Yes, I know, you could just record both tracks into your DAW, send them to a buss, record from the bus to a mono track and hide all the unused tracks. Not so simple and clean. Something cool about committing to one track for your final guitar tone blending two mics. Only one track to deal with. 

Example:
On my Fireface UC with two mics feeding analog Mic in 1 and 2. Set your mic levels and then send the output of each mic to let say ADAT 8 HW out. On the ADAT8 HW output channel Select “Loopback” to on and now the audio of the two mics will be returning on ADAT 8 HW input chan (you won’t see a meter level ). Now in your DAW create a single mono track and select ADAT8 as your input. You can do the blending in TotalMix of how much you want of each mic source. You can also save a snapshot in TotalMix for this whole layout for a quick way to jump back to this scenario. Hope this helps someone.