Signal tube versus power tube, sound impact?

Going on about 30 years ago I spoke with Andy of Vintage Tubes (in Michigan) with basically this same question. I was interested in retubing (with NOS) a pair of ARC VTM 120s (6922s and 6550s) and a Cary SLP90 (12au7s).  Andy's advice (which I followed) was to start "closest to you" which meant the preamp and then the signal tubes in the amp.  The improvement in SQ was significant.

A few months later down the road I talked to Andy again about output tubes, and he wound up selling me a pair of quads of NOS Tungsols (not the Russian reissues that are out there now) to replace the Svetlanta 6550s I had in them.  For as much money as I paid for those NOS Tungsol 6550s I was expecting a huge sonic dividend and I was disappointed.  I really didn't hear any improvement.  Maybe because I was expecting too much?

Anyway, going by that experience and Andy's advice, I would start replacing tubes from the front and work backwards.  And I have heard good things about JJs for the price.

@hilde45  , I am only relating to OP what I was told by Andy of Vintage Tubes many moons ago, and what my own experience was with replacing Svetlanta 6550s with NOS Tunsol 6550s.  I do not claim that either Andy's advice or my own experience is gospel that will apply to everyone. 

We have one answer that says power tube> signal tubes and another that says signal tubes>output tubes.  Hmmm.

. . . and actually, it looks as if it was two answers for outputs>signals versus one answer for signals>outputs. . . .

I will preface what I am going to type about JJs and EHs by emphatically stating that I do not have the golden ear, I do not own a tube tester, and I make no claims whatsoever to be a tube or audio guru.

My current preamp (SLP 05) came with six EH 6SN7s (two for the left and right balanced inputs and the other four were the left and right gain stages). I had the good fortune of getting numerous pairs of moderately used vintage tubes to roll in the balanced input sockets and I heard significant improvements with some (not all) of them. In the past, what I had been MOSTLY hearing was that the EHs were crap and that JJs were not bad for the price, so I recently took the remaining four EHs out and replaced them with JJs from Tube Depot. I thought that I heard an improvement, but I will admit that, on this, I may have been hearing confirmtion bias.

The generous individual who gave me the deal of a lifetime on those numerous pairs of vintage 6SN7s (in those two balanced input sockets I am currently running a pair of ’52 Sylvania "Bad Boys" that I got from him) also told me that he was done chasing NOS signal tubes (he no longer runs 6SN7 based gear) and from now on he is sticking to JJs for signal tubes, and to quote him as best I can, he told me that for his money, JJs were as good as it gets now. He actually favorably compared JJ 12AX7 sound to Telefunkens.

. . . what a representative from the sales department at Cary Direct once told me (the Cary people will actually talk to you on the phone if you want to buy something) when I called to inquire about the Amperex Bugle Boy 6DJ8s that Cary Direct was listing:  "Tube rolling will make you neurotic."

That is a direct quote. 

And yes, I did buy a pair of those 6DJ8s for the front of my Cary V12.  I don't recall being overly impressed with any changes to SQ I might have heard, and presently those Bugle Boys are back in the "tube drawer" of a file cabinet I have and I have a pair of Gold Lion 6922s in those sockets.

. . . I also meant to say that although I personally never heard huge sonic differences when I was going back & forth with different HEALTHY output tubes in my first two 6550 based amps (I have never rolled tubes in my present EL34 based amp as long as it was running with HEALTHY tubes), if I had an output tube or tubeS that were getting sick or were getting tired, replacing output tubes was then  like listening to a new amp.

@akgwhiz  , it is always good to have spares.

Seems to me the preamplifier tubes Carry the most weight when dealing with the sonic signature.

This has been my experience, except in the case where the tubes in my amp were getting worn out & tired.

Shirley you must know that this flies against common wisdom that pairs tube preamps with solid state power amps. 

@mambacfa  , I cannot find the post in which Shirley weighed in on this one. 

I think they are shooting themselves in the feet when they put JJ tubes, which consensus seems to say are lower quality, into their tube amplifiers.

Hmmm . . . I just looked at your "JJs suck" thread and counted the positives and negatives, and then I did the same on this thread, and I came up with 5 "JJs are okay or I like them" and 8 "JJs suck," is this your "consensus"? Not that it matters to me . . . just asking for my friend’s grandmother.

As far as why (most?) manufacturers don’t ship their gear with NOS or moderately used vintage tubes, my own personal theory on that is because I would think that most manufacturers buy tubes for the products that they build in bulk, and for that reason they buy affordable bulk priced tubes. If they went out and, for example, loaded up on NOS Tung Sol output tubes and NOS RCA black glass signal tubes, that would dramatically increase production costs and the cost  of the effect produced by that expensive combination would have to be passed on to the consumer, but that particular effect may not be what all consumers are looking for, so perhaps the manufacturer feels better to give the consumer a bit of a price break and let him or her do his or her own fine tuning by rolling high dollar tubes.

Or maybe not. I make no claims to being an audio or tube or electrical guru, so that is just a theory. Maybe pose the question to some manufacturers.

Amp manufacturers know that people are going to roll tubes anyway - it's part of the charm -  so why not let them do that for themselves.

That is also what I think, @bolong  .  +1.