Can active (self-powered) studio monitors be plugged into an audio interface or mixer with phantom power?

powered amps sound mighty good, but you have hit on their main limitation: no volume control. a simple audio interface is just that: simple. they too do not usually offer volume control on the monitor out, you are supposed to set levels in the computer program, not the interface. i think you best option would be a USB mixer, Firewire will be out-of-sight expensive, same for midi control. the alesis multimix 6 is about $100 and has most but not all of what you need. To get all your wishes you are looking at $800 at least.