Seeking Recomendations for -1000.00 amp

I have Von Schweikert VR4 Gen1 speakers. And would like some recomedations for a new amp as I recently sold mine. Used is fine. I am curious what some fellow Agonr's may recommend.
McCormack DNA 125
Quad 909
Conrad Johnson MF2250
Audio Research D130. Great-sounding underrated amp available for less than $900 on Audiogon.
ARC VT-60 I paid about $800.00 for it on the Audiogon.
Thanks for your responses. I will try to spend some time over the 4th holiday weekend learning more about these. I do appreciate your help. The McCormack is an intersting suggestion, the guy I bought my VR4's from a few years ago was using a McCormack amp, but I cannot remember which model.
Marsh A400s.