I had tried Rogue Magmu Cronus II fitted with Telefuken 12 Ax7 and Ampex 12 Au7, it sound sweet with good tonality but it clipped occasional at climax of orchestral music. https://www.soundandvision.com/content/tube-amps-pocket-change-nobsound-ns-08e fitted with Nos RTC 5654 RT tube sound fantastic with HD 800s. I connect this from headphone output of Dave using 15 ft Grado extension cable. I had tried the output of the above amp with headphone to RCA adapter to Jot R. Oh my god, Sr1a sounds much more musical with less aggressive trait but also with slight loss of transparency. Since I am happy with this result, I had ordered more Nos RCA and Sylvania 5654 tubes for tube rolling about 20 minutes ago. Audio depends on personal taste. I firmly believe that Nos tube amplification in front of Jot R will help to make Sr1a more musical.