[CJ[_2_]]

there are 4 inputs on the back of the NAD 2200 poweramplfier. "LAB"
and "NORMAL" L and R. Neither says mono. There is a switch for bridge
mono which of course i have selected. I thought i'd need to feed both
the L and the R sides of the poweramp the same output from the preamp.
I think what you're suggesting is feeding a single poweramp input
should suffice.

If I recall correctly from privious NAD amps, the 'Lab' input was a full
freq range input, while the 'Normal' input had out of audio band frequency
filtering applied.

Normally if a power amp offers a bridged mode then you connect the speaker
to the Left + and Right + terminals and connect the preamp to just one of
the channel inputs. The amp inverts this signal and feeds it to the other
amp input internally. I'm surprised which one to connect to isn't marked
but a quick bit of trial and error should work it out if you can't find the
user instructions. Obviously power down the amp when swapping the input
connection!!