Pacific Valve Dac 60...Tubes?

Recently found what I thought was a good deal on a dac 60 so I decided to give it a try with the duet as a source. Have only listened a short time(olympics have interferred)and so far am very happy.
This was a used unit and I have no idea of the condition of the tubes so am considering ordering a new pair. Would like to stay in the $100 range if possible. Any recomendations including source if possible appreciated.
What tubes are they? If you tell those of us who don't know the Pacific Valve DAC 60 like me. We may, still, be able to make some suggestions.
Sorry! Should have mentioned that.
According to the Pacific Valve site they are described as "6922/6DJ8".
This is my first experience with tubes. A bit of research showed there are many 6922's and 6dj8's. How does one know which are better? Also, is there a site that gives a description of the sound characteristics of different tubes and which can be substituted for which?
A little more research shows the tubes to be Sovtek 6922's. Discussion reveals these are about the poorest of the 6922 so I am looking at a pair of Amperex ECC88 Holland A Frame Orange Labels. Just want to dip my toes into tube rolling so these will be used but tested. Any other recommendations would really be appreciated.
Try the JAN Philips NOS. Nice sound for cheap...
I own the non-Pacific Valve modified DAC-60 and replaced the stock Sovtek's shortly after acquiring it. While I noticed better bass response, improved system speed, and gained a fair amount of blackness by going with a DAC, something seemed to be missing. So, I went with a pair of JJ Tesla's from Upscale Audio at $30/each. These tubes were very smooth, airy, and made the Sovtek's seem congested. After reading a few glowing reviews on the Amperex 7308's, I figured that I'd give them a try. Wow! Where the Tesla's left off, the 7308's took them to another level. These are much more detailed and warmer sounding than the Tesla's. While they were $80/ea from Upscale Audio, they were well worth it. much more detailed and warmer sounding than the Tesla's. While they were $80/ea from Upscale Audio, they were well worth it.
Thanks for the suggestion. Hadn't even considered the Jan Philips. Will be keeping an eye out for a pair.

The 7308's are a bit pricey but from what you describe it sounds like a buy it now or buy it later. Might be best to just skip the in between and get close to the top. Will be watching for a pair.
Thanks to you both.
Bought a used pair of Amperex BB 6dj8. Very nice compared to the Sovtek.
Am still looking for the right tube. System composed of:
Squeezebox Duet
Dac 60
B&K Ref 20
Bryston 3bst
Gallo Ref 3.1
Sound with the bb is very nice on good recordings but on older Rock cd's it is a bit fatiguing. Seems I may need a little warmer sounding tube. Any suggestions?
Am looking at a pair of Amperex USA PQ 6922 but they may be out of my price range.
Thanks for any suggestions.
I have the GR Research Modded Dac 60 and it is a fine unit with the right tubes. I had a huge stash of 6dj8 family tubes. As nearly always the Amperex are favorites.
Amperex Orange globes- best top to bottom
Amperex BB- little warmer and more plump bass
Siemens chrome plates- great all around/ detailed and expansive but thinner than the Amperex
JAN Phillips- best bang for the buck- highs not as sweet as Amperex
Mullard - Toe tapping fun, warmer and little looser bass- Musical less detailed
NOS Ei- very good top to bottom but slightly less textured midrange
Ediswan- good all around but less spectacular than Amperex, Seimens, Mullard
Thanks for the list. Just bought a pair of Amperex Orange Globe. Anxious for them to arrive.
Good deal Steve- list the date codes here when you get them.