If I recall correctly I seen a few used TRL Dude preamps that had an option volume control along with the core requirements you laid out. There are a number of rightly regarded members praise it somic capabilities..
Who makes this Pre-amp?
Octal based 6NS7 or 12NS7, 4 inputs, 2 outputs, tube rectified, point to point wired with top shelf parts. Remote control, at least volume control is a must. One balanced input and one balanced output a plus. HT by-pass is not necessary. Dual mono would also be nice but not necessary.