True, NOS/new old stock, NIB/new in box, matched quad 6H23N-EB = 6N23P-EB vacuum tubes, made by the Reflector Corporation, are compatible with 6922, 6DJ8, preamplifier tube sockets, this preamplifier tube, was designed for maximum durability, reliabilty, and sound quality, This is one of the best, Russian preamplifier vaccum tubes available,,,,, the Audible Illusion preamplifiers, uses the Reflector 6H23N-EB/6NP23-EB, Btw, these matched Russian quads were purchased, as surplus backups, from VivaTubes.com, for my audiophile system, but now, I'm offering them, at an much lower price, these preamplifier tubes have an excellent balance, with nice frequency extension & liveliness! These Russian 6H23N-EB/6N23P-EB preamplifier vacuum tubes, were made by the Reflector Corporation, in Saratov, Russia, and they also make most of the audio vaccum tubes, marketed by the New Sensor Company, in New York, USA. Btw, Decware amplifiers, also use these types of preamplifier vacuum tubes.