Thanks very much Jeff. That did it. I'm not sure how it happened, but "Merge audio to mono" was checked in both PT and RB. I had looked for a setting that was causing the problem, but just didn't dig deep enough.

With the merge to mono setting selected, the L+R mix output was recorded to a blank stereo track. That track was then rendered to a stereo .wav from the (Track - Save Track to File...) command.

The song also rendered successfully at 24/48 without distortion or over saturation, which presumably was the result of the mono merge.

Thanks,
Drew


Windows 10 Pro build 6.2.9200
Intel Core i7-3930K @ 3.20 GHz
64 GB RAM
NVIDIA GeForce GTX 650