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.
listen to good recordings with the human voice...does it sound natural and real? see if you get an impression you are listening to music not equipment, you should get a positive emotional response that is hard for sand amps to produce
try the amp on your own speakers is the best advice

btw I have read good things about the Sophia Baby

good luck
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what amp and speakers are you using now?
in general you can expect better mid-range, a more natural sound, possibly better soundstage - and some 'rolloff' in the bass. if you want to hear what they do well, bring mid-range heavy (voices, jazz ensembles, acoustic instruments). if you want to hear their weaker side, bring your bass-heavy recordings.
Must do the audition in your system, so get a dealer loan. ake a look at Cayin, great sound and value.
I just paid 450 for a Jolida FX-10 12 watt amp for my office. Sounds nice. Way to dip your toe in the tube ocean.
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.

snap it up!
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.
"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?"

You may hear some hum or slight noise with any amp, maybe more likely with tubes that SS. I don't see it as the huge deal that Ckoffend seems to believe it is.
CK - Did you get burned buying a noisy amp or something?
I picked the Baby up yesterday. It is, in fact, dead quiet and in nice shape. I've run a few pairs of speakers through, knowing they are not, on paper at least, good matches, but with nothing to lose. Klipsch KG-2, Energy Pro 22, and Spica TC-50. None very satisfying. I thought the KG-2 might have been a good match, but no dice. I do have some older Dynaco's, the A-25 and A-35, how would these fair? The only higher efficiency set I have are an Infinity P-FR, but these are going to need some work. I could also go the DIY route and get some Fostex 206 or 207 drivers for $200 or so the pair. The previous owner had Sequerra Mets on it, I've got some feelers out already for a pair of those. Anyway, any ideas in something easy to get and $300 or less for the pair (used, definitely). I'm using a DVD-A player I've had good results with on my main rig, I don't think the source is the issue.