Signal tube versus power tube, sound impact?

My mono block has eight KT 88 tubes(power tubes) and six smaller signal tubes. I'm using the stock tubes that came with each Mono. I think they are JJ tubes.

Rather than replace them all would it be best to change out the signal or the power tubes? Not sure how good the JJ tubes are but I hear they may not be the greatest.


Not knowing what your tubes are definitively (did you actually confirm they’re JJ - you seemed uncertain…), nor the amp, speakers etc., this is not a realistic query for anyone to field.

More supporting input due from ya. 😉

In my experience with my Decware amp, it’s finding the right combination of tubes that is the key. The stock tubes that came with mine were really good. Then I started experimenting with different combinations and since I had several of each type, I ended up with 12 different possible solutions. 

In the end, I found that a ~1960 vintage Telefunken signal tube and generic Russian $28 power tubes were the best sounding.

Usually power tubes first then signal tubes in an amp. Also it’s the first signal tube in the series for a particular channel that has the most impact. For instance, if you have 3 -12 ax7s  for each channel, the first one in the series has the most sound impact, the others less and less as you go to the last tube in the series. 

Amperex Bugle Boy

f your amps are running 12au7’s the Amperex Bugle Boy tubes placed in the central "gain" positions can be very good. However, buyer beware as I have heard these are sometimes Asian fakes. The two linked above look almost too good to be true - usually the vintage tubes show wear to the Bugle Boy logo. If these are real, they look exceptional.