Importance of input tubes to sound quality?


I've been running  good pair of Mullards in the input section of my LSA Statement integrated for almost two years now and was contemplating rolling them for a really good pair of 6922's. The Mullards replaced the stock tubes and made a slight difference in the openness of the stage, though that may have been confirmation bias.

Before I drop several hundred dollars on a pair of tubes, do different levels of input tubes really make a difference in sound? Can they do so on a physical level (as in, is it physically possible for them to do so)?

Ditto for the stock 12AX7's in my Jolida phono stage.

 
simao
Of course they do but I'm sure there are a lot of folks who just aren't tuned into the degree of difference they might make. Some times it is fairly subtle and sometimes it is obvious depending what your equipment/set up is and how developed your listening skills have become. Tubes have a basic sonic signature. If you know how you want to change the tone, etc, of your present amp just tell folks what you are presently using and what you want to get and you should get some specific recommendations. 
Okay. But how does the sonic sig of input tubes differ from that of output tubes?
An input tube is just a "baby" output tube, It takes the signal and increases the voltage, same as an output tube.
Tubes are made with different materials, spacing ETC ETC and thus they all sound different.
Same as how cables or capacitors sound different.
A good basic read is "Joe's Tube Lore".
While you're results may vary from his it is a good starting place.
Read that first and then let's see if you have anymore questions.
Most of all have fun with it and enjoy.
If the small signal tube is used in the amplification stage (pre driver) of your integrated amp then it will have a significant impact on the sound quality. I've had better results rolling driver tubes than output tubes. 
Simao, based on your original post I also was hoping to get more feedback on the relative benefits of rolling driver vs. output tubes, such as that provided by brf.  Good thread!  

I use a tube all pre with a SS amp. While I realize the pre has driver and output tube stages, within the context of my entire system I consider the preamp tubes to all be driver ones. 

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The input tubes on our amps are the most important to the sound, assuming that the power tubes are good. The fact is if the input tube does not get it right, the rest of the amp can't make up for it.
Thank you, atmasphere. I was hoping you'd chime in.

And thank you to everyone else, too. Looks like I'll be rolling soon!
When I picked up a pair of mono amps used last year the owner had put in a pair of NOS  RCA 12ax7 in the input stage,   I tried several modern 12AX7 and nothing came close....  the 6922 driver isn't as critical and I'm hard pressed to notice any difference in that position .  
^^ FWIW 12AX7s and 6922s are **not** interchangeable.
Yes input tubes are extremely important. They can change the flavor of the system no doubt.
Atmosphere, These tubes may be interchangeable in an LSA amp. As I recall anyway.
FWIW I think I was wrong about tubes in this amp. So far I've only found reference to the 6922's and atmosphere is right with this amp. Now if I could just remember the amp I was thinking about. Italian perhaps?
The LSA can only take 6922's. Upscale Audio has a bunch of them at various price points and quality (that's where I got the Mullards from). I just remember someone at some point saying that the input tubes (like on a pre- or in a tube-cd player or whatnot) had little to do with the sound.

However, I'm not sure how much stock I put in that.
FWIW I think I was wrong about tubes in this amp. So far I've only found reference to the 6922's and atmosphere is right with this amp. Now if I could just remember the amp I was thinking about. Italian perhaps?

No- the two tube types are simply not interchangeable. They have different pinouts as well as different specs.
Brent jesse recording gives you athe least 90 days warranty and several weeks 
To see if they are to your liking.  You can speak with him he has lots of bargains 
at decent prices on True New Old Stock  Vacuum Tubes.