Low Volume On One Amp of Pair (MKIII)

So I have my MKIII pair up and running; they sound good, not a lot of hum or hiss but one amp has a lot less volume than the other. I re-did these 10 or so years ago with the VTA boards so the 470K resistor is not present... I am not sure where to begin troubleshooting other than I did switch out the output and rectifier tubes with no changes noted.

Just a thought, but have you tried swapping the inputs between amps to verify your source is good?

I should have mentioned that I did do that as well. Thanks.

snip73 wrote:So I have my MKIII pair up and running; they sound good, not a lot of hum or hiss but one amp has a lot less volume than the other. I re-did these 10 or so years ago with the VTA boards so the 470K resistor is not present... I am not sure where to begin troubleshooting other than I did switch out the output and rectifier tubes with no changes noted.

It makes me think that this is no Dynaco MkIII. If they are something else
and you want intelligent answers you should post correct schematics.

Schematics here. No disrespect; I just assumed there might be a common "go to" point for troubleshooting that didn't require posting them:

https://ibb.co/6tBHbnR
https://ibb.co/x2Cr8Zc

Have you tried swapping tubes between the good and bad amps?

The amplification is basically set by the quote R7 / R5 , the resistors in the feedback chain.
This is provided that the amp works without dist and is able to pull full power, if it distorts and/or
cannot produce full power it might be one side of the phase inverter that has problems.