I still have a big pair of Kefs on the floor and behind me in the bow window 2xWharfedales wired Hafler (simple to do).
Very good depth on live recordings.
Wikipedia on Hafler says
"In the 1970's Hafler promoted "passive pseudo-quadraphonics", an inexpensive method of recreating ambient sounds at the rear from ordinary stereophonic recordings. Known as the "Hafler hookup",[1] this consisted of two similar additional rear speakers, connected in series (typically 8 + 8 or 16 ohms total) between the live feeds to the front speakers."