For chamber music, small ensemble, and solo instrument, Sennheiser HD600 or its upper series with DHT SET (singled-ended design as opposed to push-pull) amp will be fantastic.
I build my own tube amps as a hobby and use DHTs such as 71A, 45 with excellent result with these types of music over headphones. Not sure what is available commercially, but want to mention that tube amps have different designs. Singled ended design with DHT tubes sounds best to my ears.