I have two MP1s to drive long cables at line level, for ultra portable situations, and for backup in case of main gear failure. They aren't a high-end preamp but nothing else out there is as versatile, as easy or as reliable. I even used them in a pinch once for ribbon mics on an opera recording -- it worked out great.
P.S. 48 volts for phantom power can be generated from 3 volts using a multiplier circuit like those in a camera flash units. Camera flashes rapidly discharge a rather high voltage capacitor whereas phantom power typically requires a very small amount of current discharge -- so small that the multiplier can keep it charged from 3 volts while in use.