Auditioning a Tube Amp


I've never heard tubes and am seeking my first purchase. I'm going to be buying local and auditioning. What should I be looking and listening for to ensure everything is on the up and up? I'm leaning towards something newer like the Sophia Baby so as to not end up with a "project." Any specific tips appreciated.
smata67
Make sure it is dead quiet. There should be no buzzing coming from the amp or the speakers. If there is buzzing, don't buy it, there is something wrong! Anybody that tells you that you are supposed to get buzzing or hums from a tube amp has only listened to "broken" or poorly designed tube amps. There is no way an amp can convey good sound, an accurate sound stage and well reproduced music even if the music has higher volume than the background noise (noticeable buzz or humming from the speakers). If it is dead quiet when you listen to it someplace else, it certainly won't be when you get it home. Never buy a used tube amp (or any amp for that matter, especially on-line) without requiring the selling to state that the amp is dead quiet both at the amp and through the speakers (with speakers that are at least 88 db(A) efficient). If an amp seller states that some buzzing is part of the tube amp protocol, run like the wind for that purchase.
My current main setup are Odyssey Stratos Monos, Thiel CS3.5, Denon PRA-1500, and Oppo DV-981HD. I'm actually very satisifed with what I'm getting out of this system. I'm thinking of a low powered (and cost) tube amp for a secondary system. I understand that I will need a higher efficiency speaker. I've had good results with a Klipsch KG-2 and a 7 watt (8 ohm) TA2024 based amp, but if I need to get some better higher efficiency speakers, so be it. Maybe the subject of another post. I also have a number of lower efficiency classics laying around ADS L810, Dynaco A-35, Spica TC-50, and Energy Pro 22 among others.

I've been listening alot to Knopfler's Kill To Get Crimson lately, I'll bring that along for the vocals and maybe some Acoustic Alchemy. The Baby is noted for being dead quiet, but what if there is just a hint of buzz? A bit is acceptable for SS, is it not for tubes? I think I'm going to pick this one up for under $300, so I can splurge a bit for some new tubes or a checkup by Sophia if necessary, as I'm in the DC area. The owner has put in Western Electric tubes and seems very knowledgeable, probably an A-goner himself.

What about the tubes themselves, is there something that can be discerned from how bright they are or
aren't, how they light up or dim on power disconnect? I can compare them to each other, but have no real feel for what is normal.
Try to arrange for a time when you can have an extended audition. Don't fly through tracks seeking a demonstration of sonic acrobatics, that's the forte of solid state, IMO. Just relax and listen to some of your favorite sides without cognitive analysis. I regard a good tube amplifier's ability to keep you involved and draw you deeper into the music as a major relative strength.
Consider auditioning a well broken in set for a weekend. A good store will let you take home a demo -- with or without a credit card imprint in case you take off with it.
Everything is different. Highly subjective.