For years I have been running my 7B STs with an ARC LS25II, with excellent results. I now have an opportunity to pick up an ARC Ref 5 SE at a good price. The output impedances of these two ARC preamps are virtually the same, and ARC specifies a minimum load of 20K ohms for both units. My 7Bs have a nominal balanced input impedance spec of 20K. Can anybody see a downside to running the 7B STs with the Ref 5, like possible bass roll off? Does any forum member run the Ref 5 with 7B amps? Thanks!