2 REL Strata Subs and Mono amps

Thanks for all of your input.
My issue deals with the specific nature of my Audio Research VM220 Mono Bloc
amplifiers. They accept BOTH balanced and single ended inputs with a toggle switch selecting the appropriate configuration. So....I'm not clear if this specific amplifier uses a differential circuit when running balanced. Also am I safe using the black speaker binding post if running single ended? Overall, a confusing mess. It's not clear if the chasis screws can provide a safe ground connection.
Of course I called Audio Research a number of times and have not gotten a call back. This is a similar experience other Audio Research owners have had since their sale.

Can any one help?

Thanks

Hifigeek,
Many thanks.
It's just so frustrating to get no tech support from AR after so many years as an owner of MANY of their products, and, having had such good customer service over the years.

I guess nothing stays the same.
Other than audiophiles supporting one another.

Happy New Year to you as well.
All the best.

J Dolgin

Amazing....how complex the solution can be for a seemingly simple question.
Oh well, I guess in the hiigh end game NOTHING is ever simple.
Thanks everyone.
jdolgin