@millercarbon I have Bryston 7B3 amps which have a very low input impedance (7.5k unbalanced / 5k balanced) so I stuck with a Bryston Premp which has an output impedance of 72 ohms. This is my concern.
Yes well there you go. So you know first hand just how limiting one choice can be. Its very easy if you're not careful to wind up with a system so precariously matched that changing one thing means messing everything else up- and so that in itself becomes a huge obstacle to improvement.