Listen for a few months? If you knew what was in store for you to improve your amp, you will not wait at all this long. After a week or so of casual listening to burn in the amp, you should be able to sit down for an hour or so with your favorite music and then try ANY of the tube sockets with a few different brands. Be prepared to be shocked that first time. This would likely take a few nights for each tube. Repeat the process for the other sockets as you acquire various brands for each.
I have a pair of amps that use a 12ax7, 12au7 and 6922 per channel on the front end. Changing any of these makes a significant sonic improvement from the crappy Sovtek, EI and Electro Harmonix stock tubes. From my experience, it rarely matters where the tube is in the circuit. Each of the stock tubes is causing destruction to the performance capability of that amp.
The result from this process for my current amps, was that the edgy trebles are gone, the dynamic contrasts dramatically improved (mostly from the 12au7 swap) and the midrange becomes very smooth (mostly from the 6922). The 12ax7 was a nice improvement in tonal coherency and clarity. All of these as a new set took the amp to a level that I suspect even its designer had not observed. It is very likely that you will achieve similar benefits with your patience, time and effort here.
And learn about various tubes types (with different model numbers) that can be used in place of the tubes in your amp. This knowledge can help take your amp to another level of performance as well.
John
I have a pair of amps that use a 12ax7, 12au7 and 6922 per channel on the front end. Changing any of these makes a significant sonic improvement from the crappy Sovtek, EI and Electro Harmonix stock tubes. From my experience, it rarely matters where the tube is in the circuit. Each of the stock tubes is causing destruction to the performance capability of that amp.
The result from this process for my current amps, was that the edgy trebles are gone, the dynamic contrasts dramatically improved (mostly from the 12au7 swap) and the midrange becomes very smooth (mostly from the 6922). The 12ax7 was a nice improvement in tonal coherency and clarity. All of these as a new set took the amp to a level that I suspect even its designer had not observed. It is very likely that you will achieve similar benefits with your patience, time and effort here.
And learn about various tubes types (with different model numbers) that can be used in place of the tubes in your amp. This knowledge can help take your amp to another level of performance as well.
John