best headphone amp for Denon AH-D7000s

So I just recently upgraded my headphones to the Denon's and am absolutely loving them. However, my audiophilia nervosa is acting up again, and I'm starting to wonder if my channel island VHP-2 is the best match for them. I'm thinking of either getting the VAC-1 external power supply for the VHP-2 or upgrading to a better solid state amp. I am considering:

headamp GS-1
rockhopper m^3
musical fidelity M1HPA
BC hat peed thingee 2

Has anyone either compared any of these with the VHP-2, or heard the VHP-2 with the addition of the VAC-1 power supply?

Thanks, greatly appreciated