Louder on one channel

make sure your ears are not clogged.

Could clogged ears affect meter readings?

You didn't say how big is the difference between the two speakers.
Over the years, I have had this type of issue twice, but the difference was subtle and it moved the soundstage towards the left (my left speaker was producing less sound):
a. Once it was fixed by pulling the speaker few cms out, and changing the toeing to match the other speaker.
b. Most recently, it was one of the speaker wire connectors connecting to amp. Once I replace the speaker cable, problem was fixed.

All the best!

Had this issue.
switch the speakers, and listen

Left  speaker is at an opening to a larger part of the house, right is in a corner, right always sounds. Better, it’s in a corner, where as the left loses some oomph to the stairwell, and open part of the house.

could just. Be acoustics. as mine is.

i switched the speakers so many damn times, but always the same, 
i came to the conclusion it’s the “ROOM and acoustics”
not the amps, or speakers, cabling. 

Just my my two cents 

Not trying to be a smart aleck, but make sure your ears are not clogged.   I always have to clear my ears before and during long listening sessions.

One of the great audio questions. Even better than, why am I getting hum out of one channel? 

Have tried two different inputs, same result. Will try direct line straight when I reconnect it.thanks

Have you tried engaging / disengaging the "Line Straight" button?
 
There were reviews suggesting the balance knob is off, and it will be disengaged when you use LS.


This was one major disappointment from the reviews, but my unit doesn't seem to have the issue.

Best,
E

Does it do this on all the inputs?