I am driving these SR009 with Stax SRM-717. I have no personal experience with other Stax amps though I’ve heard the 353X is no slouch for these (and they are much easier to find used than 717). I heard these from a Chord Dave > BHSE when I auditioned them recently. Do my rig do them justice? I think so, as I don’t remember the sound being so vastly different with my audition. The SR007 I read is much harder to drive though. What I mean is if you know the sound is what you want, there are used Stax amps that won’t break the bank so don’t let that hold you back :)