Signal tube versus power tube, sound impact?

all of the above but try the small tubes first, you may find you tune the sound to your liking without expensive power tube trial and error experimentation.

jj tubes are like $40 apiece and the cheapest versus others in the $80 to 150 range

I’m looking for a cleaner Open sound. There are for preamp tubes and it seems this tube is the beginning which sets the stage for the signal and then the power tubes. So I guess starting at the beginning of the food chain makes more sense.

Although I do hear that the JJ tubes are more durable and reliable which is why I guess they use them as stock tubes.

What kind of amps are you running? 16 power tubes? WAG, but sounds like some Primalunas I've seen, but not heard. What kind of 'signal' tubes are you running? What kind of pre-amp are you running, with what kind of 'signal tubes?

Specificity might get you a better quality of response. 

Although I do hear that the JJ tubes are more durable and reliable which is why I guess they use them as stock tubes.

Says who, JJ? 😂

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.