I'd check with Ralph at Atma-Sphere on how his amps would work with VSA. I don't think I have seen that combo. But I do love Atmas. And my VSA VR-4s.
But looking at that list, I would upgrade your source and get a preamp (**ducking to avoid the hurled "no preamp is the best preamp" cries**).
There are some great DACs between $2-4k, Orpheus Prism, PS Audio, Berkeley and Antelope all come to mind.
And so many great preamps are out there. At your budget you will be able to get one with the detail of a passive/no preamp set-up and the oomph and drive of an active pre.