It took me a while but I now have applied advice found on TS to mix files from two different recorders with Audacity. The method I use is to line up the files at the beginning, find a reference point at the end, divide longer sample by the lower sample, apply percentage in the Change Speed effect.
Currently working on a recording from last night, where I had 4 channels (stage mics / aud mics) going into a DR-680. I was sent the sbd by a fellow taper, and have entered that into my project. The sbd file is shorter, and using the above method I selected the two stereo files from the 680 and applied .00314 % with the Change Speed tool. The set was @ 58 minutes. (Set 2 is 1:42)
This worked fine, but I question if it would be better to change (stretch?) the sbd to match the other files? I don’t know how to do this yet, but will seek out how to do so. It was a pretty small adjustment, and I don’t know how much the pitch/tempo could be adversely affected. Any thoughts would be greatly appreciated. Thanks.