I own four different preamp/linestages: a Placette Active, a Mark Levinson No. 32 (with built in phono), an Emotive Audio Epifania and a custom-built preamp built by Aldo D'Urso. They are all different and I would not want to say which one was unequivocably "the best" among the four.
The best preamp without a doubt..in my experience
I have always had a thing for preamplifiers. I tried many of the best brands—just to name a few: Shindo (several), Spectral, Klyne Arts, deHavilland, Berning, Placette, Marantz. I thought I had gotten close to the top as far as preamplification goes...until I got lucky enough to find an EAR G88, which is what deParavicini himself defines his masterpiece. Well, I am dumbfounded. The music flows more naturally, more realistically than ever before. You feel like being in closer touch with the instruments or the voices. The sound is just real, and for the first time I felt like I heard a real bass in my system. It’s an old product. It was produced in the early nineties, and only in 25 exemplars. But if you’re lucky enough to find one...don’t let it go.