Ebush,
My Allaerts drives the MC phono stage of my TRON Meteor preamp (v similar to current TRON Syren pre). The MC stage includes a SUT and then an active stage driven by ECC83 tubes. I can't change the impedance on the TRON myself, but I know Graham Tricker builds them to order. I can find out if you wish, but it'll take a few days as I'm just going off on leave with my family for a few days.
Charlie