Adding a DC waveform (Saw) to the low frequency in stereo did make it COMPLETELY AND TOTALLY useful for aligning.

Great Idea and you have ears that are in tip-top shape!!!

As acoustics engineer,
Here is whats going on (Kept simple as possible)

By independently off tuning the low frequency channels, with the saw added;

your effectively time-aligning the low frequency waveforms polarity to compliment each another while the saw aides Hz cycling clarity.

you have a created a pleasurable out of phase tool,
seemingly in phase.

Quickly shoving my headphones can into my analyzer with mic (AKG CK-91) read 60 to 80Hz.

If you would like,
I can give you a complete scientific analysis, it would be my pleasure.

I have all the measurement equipment.

My Best,
Sal