Second on the warning. These aren't 100% compatible with 6922/6DJ8. Talk w/Counterpoint before trying 'em.
My Metronome CD2V Sig cdp uses the 6N1P, which is only made in one factory. If you search archives you'll find details on a couple of differently marked version, but most are close in sound.
There are lots of good sounding 6922's out there. The Electro mentioned above is definitely one of the best of them. If you want to try NOS later, the Amperex Bugle Boys have been good to me, as have been Siemens and Telefunken. The Mullards are over-rated on a relative price/perf basis, IMHO. Cheers, Spencer