I used to own a VK-500 with the BATPAK option. Lots of power reserve, but not much else.
I then purchased and sold a SimAudio moon W-5 which is far superior to the VK-500 in the way of detail, transient attacks, and even added a touch of sweetness.
Combine the articulation, speed, and sweet sound of the W-5 with the power of the VK-500, and you'd have quite an amp.
I would recommend you look at the W-5 or even the $1000 Odyssey Stratos which is rated by some as a step better than the W-5.
-IME