The SFL 1 uses only a single tube which is great because you can experiment with several brands to tune the sound to your liking for around $15 to $30 per tube. I used a Mullard nos in mine and it was sensational with a ss amp. The parts connection which is a division of Sonic Frontiers offers several and can tell you the sonic characteristics of each one.
Tube recommendation for SFL1
Thanks for those who recommended SFL1 for my Bryston 3BST amp with B&W CDM1SE and two Kimber 8TC biwired. Since I am new to Tube amp, could you also recommend good tubes for SFL1? How much do I expect spend on tubes and what are their lives in general? Thanks much. Danny.