Warren Gehl to my knowledge does some very limited design work for ARC and is key in QC by reportedly listening to every piece of gear hooked up to his reference system of a Ref 6 and Ref 150se and some old, large Magnepans before the piece leaves the factory. It was, however, Ward Fiebiger who took over the reigns from Bill Johnson in the actual engineering/circuit layouts of ARC's top-level gear including the Ref series of preamps and amps. Now does that make a difference? Probably not. Surely Warren knows enough to answer the question being posed here.Warren has made a lot of contributions to the sound of ARC and little of it has been to circuitry- mostly vibration control, tube choice and similar. Bill hired him for his ears as he was/is very astute.
Ward (RIP) may have been influenced by the Italians who have since learned to let the company do what it does best. I'm not sure where your amp sits in this since it is still current.
I have seen some pretty expensive cables over at ARC (they are a 1/2 hour drive from here) so I've had pretty good reason to suspect that they didn't support the balanced standard (else you wouldn't need the pricey cables). Here is a nice bit about how balanced line works, from the Rane (a popular pro audio manufacturer) website:
http://www.rane.com/note110.html