The 5670 is close enough to the 6922 that you can use an adapter and use a 6922 in the DAC instead of the 5670. That's what I do currently.
The Reflektor '75 6N23P SWGP Silver Shields doesn't sound like a tube is in the DAC to me. With the other tubes I used, the sound erred in one direction, or there was something letting me know I had something in the signal path. But with these tubes, they just seen to get out of the way, and the music seems to come through. They're very clear and relatively transparent sounding.
The Reflektor '75 6N23P SWGP Silver Shields doesn't sound like a tube is in the DAC to me. With the other tubes I used, the sound erred in one direction, or there was something letting me know I had something in the signal path. But with these tubes, they just seen to get out of the way, and the music seems to come through. They're very clear and relatively transparent sounding.