Dave Plowman wrote:

I have an amp in each place needed. 'Separates' aren't much in fashion
these days and can be picked up cheaply - even free.

It's not the cost so much as the space needed and the extra clutter of
cabling and the like which I was hoping to avoid.

Actually, I've just discovered the perfect piece of kit which will do
exactly what I want, but it's very pricey and seem only to be available from
the USA:

https://www.amazon.com/ATNDLA6-6-Roo.../dp/B00R3HKBHU

And I would need extra remotes...

Bert