have done extensive AB w/ the maestro vs the R1, which beat other oyaides (easily), furutechs, isocleans, hubbells, and a few others i cannot mention.
the R1 is more forward and dynamic, touch better bass, but the maestro has better detail and midrange / treble resolution, very balanced, great outlet. i've ended up relying on maestros for front end gear, R1 for amps.
maestro is a great outlet. needs about a week to break in.