I'm going to give a thumbs up to Triode Lab and Frank. I have a set of 97db efficient speakers and recently purchased the 2A3 EVO integrated amp. I am absolutely floored at what I am hearing, every detail to the song, authoritative bass and airy highs and all this is combined with a absolutely well defined soundstage. I have had it for about 6 weeks to 2 months now, listen for about 2 hours every night and as I said am floored at what I am hearing.
Nice thing is that when working with Frank it starts with your associated equipment, then the music you like and he designs around that.
Good luck in your search.