Stereo sub out to mono, is it safe?

Too technical....I like music...all the best

Erikt raises a good point about the possibility of using an adapter containing a pair of resistors to do the summing. That can be thought of as a passive mixer. It would sometimes, but not always, be a viable (and less expensive) alternative to an active mixer in situations where directly shorting the two outputs together with a y-adapter would not work well.

It would eliminate the possibility of the particular distortion effect that I had mentioned, as well as whatever slight possibility of eventual damage might exist with the y-adapter approach. However, if the sub outputs of the amp are not separately buffered from the main signal path, while a mono signal would not be heard from the main speakers there would probably be a significant reduction in channel separation. A properly chosen active mixer would eliminate that possibility. Also, the high impedance of the summing resistors may or may not be sonically optimal for driving the sub, as powered subs often have relatively low input impedances compared to the line-level inputs of other components.

Regards,
-- Al

Thank you for all of the input! I will be looking into the solution suggested by Bifwynne.

Al, having made a significant investment in my system, I generally rely on the tech experts at ARC to advise me on what works and what does not. OTOH, I learned about Tom Tutay from A'gon Forum members.

The bottom line is that my solution was factory approved and works. In fact, my system even sounds better because I'm properly loading my pre. I'm sorry that some other folks may find our advice "too technical," but sometimes doing the right thing means learning a little bit about electronic, asking for the proper advice from the people who know YOUR equipment, and remediating a problem in a safe, factory approved fashion.

I know you agree with me and have said so above. My recommendation to the OP is to call the factory and ask for their advice since it's their equipment. If a custome buffer or some other sort of gear is needed, Tom Tutay is a go-to guy whi is well respected by many knowledgeable A'gon members.

That's all I have to say because otherwise I'm just repeating myself.

So . . . I thank you for your technical and experienced based advice, given here and in many other threads.

But if the OP or others want to play their systems with a one channel sub, or short out their amps, or damage their equipment -- I'm sorry for them.

Well, before tha manufacturer could get back to me the amp arrived and had a problem right out of the box so it is going back to the distributor. I will keep all of this info for the future and hopefully it will help the next person who is wondering. Thanks everyone