Vandersteen users: How low can you go with tubes

Hey all, could use some insight from people who have experience with Vandersteen 2ce speakers. I am in the process of upgrading my system, both amps and speakers. I am pretty much set on a pair of Vandersteen 2ce sigs. I noticed they are 87 db efficient with recommended minimum 40 watts power requirement. Still researching and trying to listen to amps, but I am considering moderately-priced integrated amps such as Rogue Tempest Magnum (60 watts), Unison Unico (80 watts ss), or perhaps a used ARC CA-50 (45 watts?). I would really like to go with a good tube amp but not sure I can afford the power I would need to drive these speakers, particularly with separates. Anyone have any insight about how well these speakers do with amps in the 50-80 watt power range? I listen to a wide variety of music, usually low to moderate volumes. Thanks!