Another vote for VTL over ARC. I've listened to pretty much all the brands and I've never been impressed by any ARC system to be honest. The VTL 7.5 III on the other hand is very very special. It is holographic and bodied without being overly bloomy, slow, nor colored. It's also dynamic and extended without sounding edgy nor dry
Dag amps would work well, but depends on how much meat on the bones you want. Ideally for any tube preamp pairing, the synergy should be with an amp that specializes in speed, articulation, and absolute control like Boulder. But if you want the combo to be warm and bloomy, Dag will do well.