Unfortunately this is a very difficult tube to get as NOS and the ones that sound good are continuing to increase in price. There are no good new 6DJ8 / 6922 / 7308 tubes being manufactured (in my opinion).
The Amperex 7308 may be best for your needs. This was a military tube, stunningly clean, very fast and very low distortion. When I owned ARC it was my overall favorite. The only other choice might be the Siemens E288CC. I have a bunch of these and run them in certain audio gear, not sure if the ARC will "digest" them though.
For the Amperex (USA) 7308, contact Bruce Wenger at BWS Tube. 703-536-3910. He has a large supply of the Amperex and E288CC Siemens as well. He may know if the ARC circuit supports the Siemens. His web link below:
http://www.bws-tube.com/
The Amperex 7308 may be best for your needs. This was a military tube, stunningly clean, very fast and very low distortion. When I owned ARC it was my overall favorite. The only other choice might be the Siemens E288CC. I have a bunch of these and run them in certain audio gear, not sure if the ARC will "digest" them though.
For the Amperex (USA) 7308, contact Bruce Wenger at BWS Tube. 703-536-3910. He has a large supply of the Amperex and E288CC Siemens as well. He may know if the ARC circuit supports the Siemens. His web link below:
http://www.bws-tube.com/