This is what works best in the SLO IMO. I've tried Sylvania, Winged C and the wafer 5881s were as good or better in that amp. Haven't owned an Avenger though. Chinese pre tubes just seem to work in everything.
As of now, after some tube rolling, i've settled on tung sol on v1, 8th gen chinese in the rest. EH 6L6 power tubes that came in the amp when sold to me. Might try some other power tubes later