Finally getting some new tubes in to start rolling on the Stratus. So far swapped out the stock input tube for a NOS Russian 6n1p, and got a few rectifiers in, including an EML and NOS RCA blackplates. I didn't notice much of a difference just swapping out the input tube. But man what a difference the rectifier makes!
I found with the stock rectifier the overall sound was a bit slow and warm. It sounds good on my brighter headphones, but with my warmer sets like the HD650, Atrium, Atticus it was a bit too slow and warm. It made them a bit bloated and thick. The EML is much much faster, with stronger transients and an overall more controlled sound to it. The bass hits hard and tight. I also notice the upper frequencies are more present as well. My Atrium is pretty tame up top, and the stock tube just made it too dark, lacking any proper treble/upper mids presence. That's changes completely with the EML. If there's any complaints on the EML, it's not the smoothest sounding tube I've tried. It's a bit aggressive at times, but still a huge improvement over stock.
The RCA IMO sounds like a more refined EML. It's faster and more controlled than the stock unit, but smoother than the EML, and less aggressive. The treble region really stands out on the RCA as being well extended and present, but not aggressive at all. Bass response is tight and controlled, but a bit more reserved than the EML. Overall the top to bottom response from the RCA is more balanced and refined sounding. The EML is a more fun listen, but can tire me out just a bit for longer sessions. Both though are a marked improvement over the stock tube. I think I like the RCA a bit more, but it's too early to say for sure.
Today I have a set of RCA 2a3 coming in, I can't wait to give those a listen. If the Stratus is even half as responsive to power tubes as it is rectifiers, i'll be more than happy. Even with the stock power tubes, running the NOS rectifier and input tubes really transforms the Stratus from great to amazing.