@BillOhio loaned me his DNA Sonnett 2 for a few days along with an Eitr. Audio chain was: Mac Mini -> Eitr -> Modi MB -> Sonnett 2 -> HD 6XX/HE-400i Besides meetups the only home experience I had with tubes was the Vali 2, which I thought was good but I preferred the sound of my own amp. The Sonnett 2 with the HD 6XX was a magic pairing. Everything was just so clear. I was always curious what people meant about the high impedance Senns needing tubes and now I understand. With the HE-400i I found it a bit underwhelming, but with high-Z phones this is an excellent combo. I preferred the sound with the 120ohm IEC switch. Very curious what the IEC output would have sounded like with 600 ohm Beyerdynamics. Definitely one of the most memorable amps for me.