Darkmoebius,
This is a very abbreviated version of my experience with the above preamps:
Supratek: dynamic, fairly resolving and involving, but is not completely neutral- it did have very annoying (to me) mid range glare on certain recordings. After many debates I suspect, that it suffered from some kind of chassis generated resonance (it does have fairly thin metal bottom plate), and some members reported improvement of the glare with the use of the wooden part of the chassis for support.
Nagra: very refined, involving and musical. It does have slightly different (forward) soundstage perspective, but is not bright.
Doshi: neutral and well balanced, but left me with an impression of lacking dynamic impact, compared to Supratek and Nagra, and especially to REX.
REX: It does NOT have any flaws IMHO- extremely dynamic, beautiful tone, very balanced (no pun intended), mid range is absolutely to die for, resolution in spades, bass, you name it- it does it all. Overall, it's a different class of music reproduction, compared to others.
I lied, it does have a few flaws- it is line stage only, hence an additional expense of the separate phono,
it runs pretty warm,
and it costs $22k now.
I still feel, one day I might have it in my system again, it was that addictive.
