[Sykes22]

I’m looking for a headphone amp with tone controls, and preferably with valves.
Does anyone know if there is such a thing?

[vonnie123]

https://www.usaudiomart.com/details/650218119-luxman-sq38fd-rare-115v-us/images/5682346/

This is an integrated, but you could adapt it to make it work. 

You might want to check with Schiit Audio and see if they have something that can be adapted to a standard tubed HA.

[AllanS]

+1 Schiit. Maybe separates combination of analog Lokius and Valhalla 3 or integrated with the new AsgardX plus Forkbeard for 3 band digital eq.

[Letitroll98]

There are about a zillion head amps with tubes and tone controls in the Chi Fi market, but I'm not sure you want to go there for several reasons in today's climate.  It was easy to find your criteria at Fosi, SMSL, Topping, Douk, etc.