So I’m gonna go off the reservation a bit here and recommend giving the Linear Tube Audio MZ2 (w/ optional LPS) a look as it’s very neutral and gives you that effortless 3D soundstage that tubes do so well and you usually need to pay dearly for to get from solid state preamps. Plus, it’s a David Berning design where the tubes last forever and are cheap to replace so very low maintenance.
If you must go solid state I can highly recommend either the Bryston BP6 or BP26 (they’re pretty much the same except the BP26 offers balanced connections and a separate power supply). I owned the BP6 for years and found it to be the most transparent and neutral component I’ve heard, and it throws off a big and deep soundstage with excellent imaging and separation. And while it’s not cold or sterile sounding, it won’t add any warmth on its own. Here’s a BP26 just fyi…
Hope this is somewhat useful, and best of luck.