I can't possibly imagine a better pre than an Atma-Sphere MP-1 or MP-3. I just went from a REF1 to an MP3 with my M60MkIII's. The switch was a revelation. You don't mention what options your Atma-Sphere gear has. If you don't have the Teflon coupling caps in both along with the regulator option in the MP-3, you might be better off with those upgrades for a sonic improvement. I should also mention that ultra low noise perfectly matched 12AU7's in the MP-3 along with low noise matched 6SN7's in V1 & V2 in the M60's will make an enormous improvement.
