I deal almost exclusively with Kevin at Upscale Audio, but a lot of people recommend Jim McShane.
http://www.mcshanedesign.net/tubes.htm
Also, Brent Jessee and Andy at Vintage Tube Services.
https://www.audiotubes.com/
http://vintagetubeservices.com/
http://www.mcshanedesign.net/tubes.htm
Also, Brent Jessee and Andy at Vintage Tube Services.
https://www.audiotubes.com/
http://vintagetubeservices.com/