You might want to try the Sanders Sound Systems Magtech amplifier. I have previously owned the McIntosh MC-402, Krell FPB200, Spectral DMA-200, Edge M8M and a few other great amps that I just can't think of right now. You can try it for 30 days at no cost as Sanders pays the shipping to you and the return shipping in the event that you don't keep it. I drive the big Duntech Sovereigns with this amp (by big I mean 74" H X 18" W X 33" deep and weigh in at 375lbs each) The sound is magnificient. I have owned these speakers for 24 years. And by the way, all Sanders Sound Systems products carry a lifetime guarantee. Happy listening no matter what path you choose. I'll guarantee you the Magtech amp will make your Von Schweikert's walk and talk.
"Neutral/Clear Amp vs. Dark Amp"
It seems that of the many reviews I read about amps within my price range (under $5,000 new) they always end with some reference to a "dark" sound. That is exactly what I am NOT looking for. I'm looking for a clear, neutral sounding amp that won't add anything other that a clear representation of the music. I'm thinking maybe Classe, Ayre, Pass, Sim Audio? I'd like to hear other recommendations. I'd also like to stick with SS, as I have a deHavilland preamp and it mates well with SS amps. Speakers are Von Schweikert 4.5's and I use silver wire throughout. Listen to digital and analog, all types of music. That's the key. It has to sound like music, otherwise why bother? Currently using a McCormack DNA-1. It's a good amp, just looking for a significant upgrade. Another choice is to send the amp back to McCormack and have them do some significant upgrades.