Is anyone using REL subwoofers with BAT tubed amp?

What is wrong with it that needs repaired??
What is the problem otherwise???

Since you've already tried connecting the subs to a different amp, were both hooked to the speaker terminals on the BAT amp using the Neutrik cable supplied with the RELs? Is this how they were connected to the McIntosh amp?

From BAT web site: "... it incorporates all-triode zero-feedback topology, fully balanced operation...." As I remember, REL has a method for connecting a balanced high level input that would need to be followed. Alternatively, try line level inputs from your preamp (assuming you have one). Personally I prefer the line level input despite the manual (and other) recommendations for amp connection.