What preamp for Lamm M1.2 ?

I, too, chose the Lamm L2. What a combo.

Yes, I've heard the VTL preamps and the ARC preamps create good synergy with the Lamm Hybrids. They are great choices.

The ARC/Lamm combo will always be influenced by cabling, the room, and
associated equip. Not sure what those other contributing factors are, but
they play a major role in the sound. Having said that, there are a number of
Lamm hybrid users that I have successfully married ARC Preamps with
Lamm amps. Tricon_dave, here on AGon, is one such person. He was
using an ARC Ref 5SE with Lamm M1.2s. Perhaps you should reach out to
him for actual ARC/Lamm experience. So even though we each have
varying opinions, in the final analysis, your ears should become the final
authority.