I am using Winged SEP C's. They are wonderful and true workhorses for daily listening. I don't want to ruin your vibe, but I was warned to avoid the Tung Sol 5881 due to biasing issues. Since the SE40 is a true PITA to bias, AND some 5881's don't spec well in terms of this amp. Anyhow, as much as I wanted to try some, I have avoided them. It will be a while until I need to roll at this point. 30 min. warm up and I'm in audio heaven right now...