Right, get your drift Richard. I was unaware of that. Thanks for the info.

On a more general point, surround sound can be used in many different ways, though commercial applications tend to be more specific / prescriptive but as Steve points out it basically amounts to a set of independent channels and I'd add, almost any amount of them (I know people who work in 64 channels in experimental music applications / software at specialist facilities) and even in 5.1 there are several different perspectives one can generate for the listener, not simply the usual cinema orientation.

well one of the most affordable recorders is the tascam DR-680... here is my video review


and write up

Tascam DR-680 Review

Using the Soundfield SPS 200 (about £1,500) and a 4-cnhannel recorder will do it.

BUT - the recorder *must* have four accurate mic. pres that can all be controlled together or you mess up the relationship between the capsules.

My Nagra VI will do this - I'm not sure about others.

Maybe usw an R-44 with the Soundfield matching pre. and feed line-in.