IGS Audio - Here's the list of compatible input tubes for the Tubecore 3U fitting in the first socket: 6N1P-EV - stock tube, ECC85, 6AQ8, 6BC8, 6BK7, 6BQ7, 6BZ7, 6DJ8, 6DT8. | Facebook
Schiit Audio: Audio Products Designed and Built in Texas and California
True NOS NIB GE USA 6BZ7/6BQ7A 2 Grey Plate Top O Get Vacuum Tube 100+% - VIVA TUBES