Oh my goodness, I love tubes. I even want one of those cool tube clocks!
For me, it’s the NAD C658 all-in-one (preamp, DAC, streamer, DIRAC). The feature set sounded incredible and it used BluOS which I was familiar with from the Node I previously owned. I paid for the complete DIRAC version, invested in mic stand and purchased a UMIK. It sounded good for only a small portion of ownership, but I suspect it may have been due to a really good sweep in DIRAC. Great feature set, but never sounded musical and “right” in my system.
Confirmation bias? 100%. But confirmation bias slowly goes away, too.