I would strongly recommend a BAT VK30se or beyond (balanced.com),McIntosh C2200, Aesthetix Calypso +, Audio Research, Conrad-Johnson. USE CAUTION with the Vk-50 series and higher, they only have balanced in/outs.
Maybe Atmosphere.
I think your ears will answer the dual-mono vs traditional. But I can say this it does make for a nice sound (dual-mono) and keeps noises and junk down or out. The VTL 5.5 is not truly balanced as I was told by an E.Engineer.
My Fav. system (beyond my own) is a full VTL set-up with the MB-450s and a 5.5 pre. What a system you have or will have.