Stereo sub out to mono, is it safe?

Phasecorrect, I'm not sure whose answer(s) you are referring to as "bizarre," but the original question was not which channels bass "can operate in," or whether a sub "acknowledges left or right." The question was would it be safe (or could it cause damage or other problems) to combine the left and right channel sub outputs of an integrated amplifier by shorting them together with a y-adapter.

Geared4me, the suggestion by Bifwynne is an excellent one. A line-level mixer having reasonably high input impedance, and that provides RCA connectors, would eliminate all of the possible issues that have been discussed.

Regards,
-- Al

Well...in thirty years of audio I have never had an issue combining channels to form mono from a pre out...adding a mixer seems complicated and unneeded...as does utilizing only one pre out channel...just my findings...

Phasecorrect, thanks for the follow-up.

To be sure that my first post above is clear to everyone, I will summarize it without the techno-stuff:

1)There is a reasonably good chance that the y-adapter approach will work well.

2)Depending on the specific design, there is a possibility that the y-adapter approach will result in mono being heard through the main speakers.

3)Depending on the specific design, there is a possibility that the y-adapter approach will result in a perceivable increase in distortion (or other perceivable sonic degradation) on deep bass notes produced by instruments that are positioned off to one side.

4)Depending on the specific design, there is a VERY SLIGHT possibility that the y-adapter approach could over the long term result in damage.

5)Using a properly chosen mixer instead of a y-adapter would eliminate all of these adverse possibilities.

6)Hopefully the manufacturer will provide further information that will narrow down these possibilities.

Regards,
-- Al

Al...no worries...this is audio and there are more ways to skin a cat...and I believe we all have good intentions...I just try to inform others of thje pitfalls I have encountered...this situation isn't one of those...99 percent of the time it will work...happy listening....

Don't you need a 'summing' adapter for this application?

I don't think this is the same as 'splitting' a single output which a vanilla flavored "Y" adapter would do.

But 'summing' two signals into one would take a different "Y" configuration.

The quickest example I could find was the one on Antimodes website:
http://www.dspeaker.com/en/support/using-stereo-pre-out-with-8033.shtml