I use a Zana Deux in my current speaker setup. I didn't see the point in spending big bucks on a dedicated preamp when I can have a nice headamp & preamp for the same price
Best dedicated preamp I've owned was a BAT VK-5i - $5K msrp, $1700 or so on agon. It's been a while, and I don't have hard comparisons on the same system, but I don't miss it a bit. Intuitively I'd definitely take the Zana Deux; all the BAT had over it was a remote control. My system as a whole now is far better, but again many things have changed besides the pre.
The System:
Tannoy Dimension TD10 speakers
Zana Deux pre
Heathkit W4A tube amps or McIntosh MC2100
Denon 3910 for digital
SOTA Star w/ FR64fx arm & Benz Glider cart for vinyl - assuming I can ever tear it away from my headphone rig (currently in a different room)
My current system's philosophy, I suppose you could say, lies in middle ground between the 2 extreme camps. The heart of the Tannoy Dimension TD10's is a single 10" dual-concentric driver that, in theory, blends the coherence of single driver with the dynamics and full range of a multi-driver system. They're fairly efficient at 91db, but not uber-efficient. Hooked up to one of two mid-power vintage amps; a 20 Watt tube amp and a 100 Watt SS, both with transformer coupled outputs. I've tried much higher powered (and much more $$$$) modern hifi amps but the result was a touch too sterile. Current result is liquid musical bliss
Have heard a multi-driver, mega-watt Thiel/Krell system that sounds spectacular; lesser implementations of the big speaks/big amps philosophy don't have the magic (it's hard to find the magic). Though I haven't heard the single driver systems, as a dynamics junkie I've gotta admit I'm highly skeptical, and not terribly interested in exploring there, yet.