Well, I just put them back into the system by replacing my Electrocompaniet ECD-1 dac with an Audiologic 24MXL dac. The Audiologic uses a pair of 6922 tubes. The unit comes with Sovteks (yuck!).
Even with the Sovteks, the Audiologic added a little texture and fullness that the system really needed. This dac has much more clarity throughout (especially in the highs) than the ECD-1. I didn't think my system could get more detailed, but it has in a very musical way. This dac has also deepend my soundstage and put more air and space around the instruments. Overall, I think the Audiologic is an excellent dac and worth every penny (lists for $4500 in balanced form - which I have).
Now for the fun part...tube rolling.
I just replaced the Sovteks with a pair of NOS Tungsram - WOW!!
Increased dynamics

(faster transient response and it plays deeper with more authority), more detail in the mids/highs while expanding the musical space even more front to back. All this ice cold out of the box.
I also have a pair of Amperex 6922, PQ, white label, US (shield, gold pins)
to play with.
Looks like a fun weekend!
Let's Go Yankees!!
George