I have never owned the ARC Ref40 or 10 so I can't comment but back when I was doing amp evaluations I owned MBL 6010d, Arc Ref3, VTL for some three years plus and VAC. I never had any issues as you mention, VAC was my favorite out of the others.
Have you had the 6010d paired up with your 9011's? What cables are you using?
Have you checked out my thread about my VAC journey? If not you should, prior to leaving and upon arrival back I had the 9011's paired up with my 101E's.
Any pics you can post showing your set-up.