Tube amp forethought


Hello, im researching my retirement two ch audio system and tube amps are in the forefront of my “wants” my plan will be a pair of QUAD ESL’s not sure which just yet

What do i need to know about maintaining a tube amp, like a AudioResearch 120 for starters or other tube amps. Biasing is totally new to me. Tube life and modes (triode, Pentode, UltraLinear) all foreign to me.

im a 40 year hobbiest so im pretty versed, this is just an unknown territory for me, thanx guys !

kgveteran
Room size: 13’x19’x vaulted ceiling
music taste: LarryCarlton jazz, SteelyDan, i will begin dabbling in some classical
near field: speakers will be 8’ from LP
Hearing ??? My hearing roll off at 14Khz
When my original version Freya arrived a couple of years ago with its stock "mystery tubes" (actually NOS Russians) they were very quiet, and displayed no microphonics. Hardly crap. I ordered a set of new version Tung Sols anyway and they sounded fine and very quiet but I wondered if NOS anything else would sound better. I eventually bought bunches of NOS Sylvanias and GEs, and decided the GEs were a little more to my tastes. Note that all of the tubes I mentioned sounded and performed fine, no microphonics or noise, just slight tonal differences as one would expect. The various Russian power tubes I've used in both my previous push pull and current single ended power amps have performed brilliantly, and really lasted...KT88s, 120s, 77s, 6550s, etc., including my current faves 7581As. 
@kgveteran So you're young enough to want the volume pretty loud! If not, the 57s will easily sound loud enough in your room, particularly if not full of soft furnishings. There's a guy in NH that will refurb a pair of 57s for a few big ones. Pros: Exquisite sounding, fast, responds to system upgrades like you wouldn't believe, louder than you might guess, what bass there is clean and fast, magical midband, transparent and sweet. Cons: May not be loud enough, needs protection circuit if you like to crank it, 7" wide sweet spot only suitable for dedicated listening. 
@clio09, though I have yet to bring my old Quads up here from SoCal, I couldn't resist the near mint RM-10 Mk.2 that has been listed here on Audiogon for a coupla weeks. As the Quads don't need (and in fact can't withstand) more than what the amp produces from it's 4 ohm taps, I'll be hooking them up that way for lower distortion and longer tube life. I'm stoked!
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