Passive preamps - differences between technologies

Don’t have the technical know-how of most on this thread but I’ve been using a Slagle/Jackson(EMIA) elmaformer for the last few years. I haven’t shot it out vs other passive designs but it did beat out a Levinson no.28 and a McIntosh c220 in my high efficiency horn system. Beautiful large step attenuated volume knob and a three input switch. 
 

looks-wise it’s my favorite piece of gear in any system I’ve had/seen

Thanks for all the recommendations and sharing your experience. 

Slightly added warmth/richness would be a lot more welcomed than any loss of dynamics. 

Simply put, I'm wondering if it's worth it puchasing something like Music First Audio Classic V2 or if the technology advanced so much I'd be better off with something else (I'm only assuming that because there's apparently a big difference between V1 and V2 while the first version isn't that much older).

Townshend Allegri Reference looks absolutely amazing but it's also rare on a used market and very expensive. Maybe it's just wrong intuition but Music First Audio would be probably the best choice in terms of performance and resale value. 

My speakers are 92,5dB, power amp's input sensitivity is 300k ohms and both DAC and phono preamp have pretty strong output capabilities. Especially with the phono (RCM sensor2) I'm suffering with too much gain from the ARC LS16 preamp. Setting lower gain on the phono stage results in muddy sound when set too low. Also, I live in the city center and the mains isn't the cleanest. So I assume my system would welcome a passive preamp with open arms :)

I gave up after ten years use a wonderful sounding dual mono valve preamp in favour of the complete quiet and transparency of detail of an Audion Select TVC line level pre amplifier (copper transformer windings w/ silver internal hook up wires) —sound is colourful, vibrant and dynamic - not in an additive way, just that it’s not greying or shrinking the sound as you would find with most alternative means of adjusting volume. Speakers are 104db horns.

OP, the 300K is the input impedance. The input sensitivity of the amp is 2V for rated output, and the V gain is 24db, a little less than the norm of 26-28 db. Just a friendly fyi. My best, and ENJOY ! MrD.

@mrdecibel Thanks! I was under the impression that the input inpedance is the main factor to determine how friendly a power amp can be to a passive preamplifier. And also the output of a phono stage or a DAC..