@whiteknee IMO original Tesla EL34s are a great sounding tube. I have two small amps that can run EL34s. My Inspire KT-88 can also run 6L6, 6550, KT-66, 77, 88, 120, etc. I have pairs of St Pete SED S, Winged C EL34s, Tesla, RFT, GE and Sovtek 6CA7s (American EL34 equivalent). The Teslas have that warm, rich, midrange, are balanced, with a touch of treble roll off, and good bass response. IMO, second only to the St Pete Svets. The Svets have a little more treble extension and perhaps bigger soundstage, although in a blind A/B probably difficult to distinguish the two.
RFTs brighter, edgier, with less warmth in the midrange. 6CA7s are more balanced than all of the above, almost clinical transparency without richness, like a studio monitor! GL KT-77 are also super balanced but with a touch more musicality. NOS Svets and Tesla rule in my two rigs.