Hmm. I wasn't too keen on it with my SA-1. A part of me is thinking that I just didn't find good amp synergy, and another part of me is thinking that I'll remember why I sold my first M1570 the instant I give my second one a try, lol. Same reason I've owned three Beyer DT770s in my life. "Oh man, why did I get rid of that headphone?" And then shortly after getting another one, "Oh yeah..."
I'm also curious about the SMSL SH-9 amp. I'm wary to try any THX amps because everybody I've seen that has similar tastes to mine dislikes them, but if I was going to try a THX amp, and I suppose I should sometime, I think the SH-9 would be the one I try. And there might be some synergy there. And it's the cheapest of the three amps I'm considering (RebelAmp, Jot2, SH-9) by half. So the temptation is strong.
Either way, the RebelAmp is my next headphone-related purchase, that's already certain. Maybe early next year.