Lower power on left channel

Hi Guy's

I have not checked the red light (bad tube indicator) I did not notice that any of them where on when leaning over the amp checking the heat of the tubes before turning the amp off, I will have to power the amp and check at the same time as changing the speaker cables over. Source wise, I have  tried change the input on the pre amp from Dac to phono pre amp, that did not make any difference.    

Addendum to my previous response-I have a non contact infrared laser pistol grip thermometer that has many uses.  Just added checking Amp tube temps to it's portfolio.  Got it at HF (20:1 ratio for less than $40 with coupon) originally to check header pipe temps on engines..  Very accurate on tubes also.

@bigred71 

 before you swap the wires, swap the tubes. Wires rarely go bad, but tubes often do.

All the best.

,

After swapping the speaker cables over on the rear of the amp the left speaker was still down on volume, I then removed the speaker grill and found that the Mid's speaker was not working. Removing the mid speaker I found that one of the connecting wires was off the terminal, after re-soldering the wire back on and refitting to the speaker, hey presto the all good.

Thanks guys for all your thoughts and Idea's 

Happy New Year

Steve.