Yes, output tubes will also affect your system’s sound/presentation. My previous octet of output tubes(in Cary monoblocks), were 1970’s, GE 6550As. Two sets of the same and a couple octets of Sylvania 6550s, before those(all mentioned being NOS, at purchase). Both of those were chosen, for their very clean, extended, uncolored sound, and wide, deep staging(like your Sylvania 6SN7s). One of the last eight shorted, after a few years of faithful service(50% of GOOD left, on a Hickok tester). Given the prices/scarcity of NOS 6550/KT88 types, I looked for alternatives. TC Tubes found a close match, for the GE 6550s, in their, "too weak to sell as new" NOS pile and gave it to me. Mean time: I bought a quad of the Russian KT88s, made by New Sensor and labeled as Genelex. With a quad of each installed, and my source in mono, I compared my amps. After a few hours, they were very close in presentation, with the(half life) GEs still having a slight edge in bottom end definition and dynamics. I have an actively biamped(bypassed during listening tests) bass system, so- no issue(for me). Now I’ve got an octet of the Russian KT88s and my ears are happy, once again. They’re pretty too! https://tctubes.com/images/view.aspx?productId=1463 The, "BEST" new production tube, would be the EAT KT88 though (to be honest), IF you’ve got the juice. https://www.tubedepot.com/products/eat-kt88-diamond-power-vacuum-tube-matched-quad Sorry for the verbosity!
