Interesting thread which I've enjoyed reading through. Your title is so apt, as it describes my hunt for a pre-amp to a tee. There are so many quirks which can disqualify pre-amps in one's particular system....no remote, poor remote implementation, no volume display, single ended only, can't drive a sub-woofer (ARC), not enough outputs, poor cosmetics....and the list goes on. And this is before even describing sonics! You have a great list and GAT 2 would be one I'd love to try but SE only is a deal killer for me.
I've been going direct from a Mytek Manhattan II into a Jeff Rowland 625 S2, and have been quite happy with the sound. I had a chance to try the newest version darTZeel pre for a couple weeks on loan from a friend who was out of town. I regard darTZeel as being at very top of audio design in every aspect. My hopes were very high. It is a beautiful piece of gear with everything done right. It did sound great, and was better than no pre-amp, but frankly I was not overwhelmed. In reality our aural memory is not that long so I'll just say it sounded very good and leave it there. Shortly after I also had use of a new Mark Levinson 523 from a friend and it was nice but not as good as the NHB-18NS.
That was several months ago, and I haven continued with my DAC direct setup and been very happy but still looking towards adding a pre. I've had my radar up on the Luxman C900-u. I've had the chance to have one in house for that last month or so and I think it is a very special piece of gear which has captured me in an unexpected way. Given my hopes for the darTZeel, I wasn't expecting a big change with the Luxman but I was wrong. Very big soundstage, superb instrument separation, prodigious bass, delicate extended highs, and the most gorgeous midrange. It is built like a tank with excellent cosmetics....and has as really good remote volume control implementation.
Sorry to muddy the waters of you list, but given my experience with the darTZeel, I think the Luxman C900-u is something worth looking into.
Great to read about the Luxman which i have read many good things about. Curious as to why SE only does not work for you? My amp is XLR only but an SE-XLR cable works well. Who knows...maybe i dont know what i am missing! However, very happy so just my two cents.