Coming from NOS RCA 5961 reds, the Cryotone 6SL7s have been transformative to the sound of the Aegis headphone amp. The soundstage jumped in size and there was a distinct increase in resolution. The noise floor is lower and the highs actually are buttery smooth as the marketing suggests. I couldn’t believe an input tube could make this much difference, especially versus the excellent RCA 5691. I’m incredibly pleased with the performance of these tubes and in this case the product is worth the premium price.
Was using a PSVane we 6sl7 before, it does sound great but I think the electrical parameters where a bit off from standard 6sl7 overdriving my amp a bit, with the cryotone I get the same resolution and musicality (if not bettter) while the amp also seem to sound fuller as I can rise the volume a bit and driver the rest of the tubes better. At least this is my hypotesis for switching to the cryotone, excellent tube for a type that is otherwise hard to find of good quality.