Euphoric Realism vs. Euphonic Romanticism

Wow. With the list of preamps you have already tried, I would hestiate to recommend anything as a sure thing for you. One preamp that is fast and not euphonic is the CAT SL1, and I imagine the new CAT Legend, but hard to really know if they will give you what you want, but they should proabably be auditioned.

Just curious, have you tried passives with your SET?

I don't know if it is the right direction for you, but when I hear "immediate, transparent and fast" - I think passive; with the quality of the volume control being critical. I think it would be interesting for you to listen to a Placette RVC which not only costs just $1,000, but comes with a 30-day trial, and has arguably the best and most accurate volume control in the industry. It may also be Euphoric, but not necessarily Euphonic - it is immediate, transparent, and fast (and silent). Worth a trial to see if it works in your system for your ears. If you are seeking a pre that "does no harm" this may work, but I find I like a bit of coloration from my pre.