Krohn Hite makes some nice equipment - I have a 3103 BP and a 3341 LP/HP and use them in designing analog front ends. They are dependable and have consistent results.
I just restored a KH 3800 Tracking filter. BW down to .001 Hz. For most things its serious overkill. The tube units were really well designed and have seriously good DC performance for tube stuff.
I am willing to send it to a happy Diyaudio'r s home if you'll pay the shipping. Not that I am down-sizing, but just too much stuff. I used to have a Krohn-Hite Museum in the basement...no more.