I've been using the Chord Etude with the Susvara and Abyss and it's pretty nice. It adds some heft and I do feel both the cans extend lower a little more easily through the amp. I got mostly the same impressions from the Pass XA25, but I might consider keeping this one a bit longer because, unlike the Pass, it runs cool and I can pick it up with one hand and not need a hand cart. It's a stunningly beautiful amp and very eye catching, especially when turned on.
Question I have for you all is do you unplug and plug headphones to the speaker tap adapter while the amp is on? I always try to be safe and turn off the amp, but is it enough just to mute the source? It's hard to A/B headphones when I have to wait 30 seconds in between! The Etude does it's thing to power off safely and tests the fans at power on, so there's a little delay because of that. I also generally just don't like turning things off and on and would rather keep them powered on.