In this instance the ‘connection’ would be by grouping the Amp’s room -- presumably without any passive speakers of its own -- with the Five pair?

It would work, after a fashion, but there’d be no redirection of bass frequencies away from the Fives. You’d therefore lose quite a bit of the benefit of adding a Sub, i.e. allowing the main speakers more ‘air’ for the mid-range. You also wouldn’t be able to Trueplay everything together.

IMHO you simply don’t need two Subs for a Five pair. I’d suggest you bond one, as normal, and locate it somewhere along the line between the two Fives.

You could of course set an Amp up with Fives as surrounds, setting music play to ‘Full’. That could support two Subs, with proper bass management. All a bit of a waste of money if you ask me.

Thanks for the excellent reply. I realize this isn’t practical but I was curious if it were technically possible. IMHO just buying a Sonos soundbar as a dual sub hub without a TV would be cheaper and properly balanced thought I agree with you the Fives wouldn’t need a dual sub and there are arguments they need any sub at all. Thanks again. 

Although many say Fives don’t need a Sub at all -- and they do go down pretty deep on their own -- I prefer to use one. It provides a little extra grunt and, as I say, frees up the Fives to work better in the midrange.

Me too.