Balance knob ..

So I'd say I've been a budget audiophile for 40+ years. Used to sell audio at Audio Warehouse in Cincinnati in the '80s. Currently I have a pretty big room with 12' ceilings, but different open areas behind each of the Maggie 1.7is and the Emotiva BASX 10" subs behind each. All driven by an Emotiva XPA-2 Gen3 and old CJ PV-10AL preamp. Listening mostly through a Bluesound Node 2i. CD player is a Panasonic Aventage BD1060 disc player. I have the sound, honestly, pretty damn great. But I am realizing a bit of bias to the left speaker. I think this is because that speaker has a lot space behind and to the side whilst the right has less and more complicated space behind and a closer side wall. 

I have always been told - and believed - that you shouldn't ever mess with the balance knob. But if the sound is a bit UNbalanced isn't that what it's for? Just to "balance" the output? But then I think with more signal going to the channel that the knob is turned to - which will screw-up imaging, soundstage, depth, etc., no? 

I am kinda stuck cuz I can't move the speakers or have a dedicated listening room. 

For me the loss mostly affects 'depth of image' on recordings which have that information embedded, not so much an actual shift in left/right imaging and loss of focus/clarity. For me the tough part in the analysis is determining when the recording's imbalance is due to instrument(s) placement on the stage or microphone placement/mixing. I often find that in solo piano music, for example, there is a pronounced left leaning balance which I have assumed is the result of microphone placement, not so much as a mixing issue. Being a lazy audiophile, when this occurs, I simply shift to the right a few inches bringing the prominent left balance  back to center. And, when all is said and done, I'm not sure how much the out of phase information is present in the recording, audible in the listening experience, or important to most ordinary (not OCD's) listeners. 
LOL jkf011, obviously we erred! I just looked at the wrong picture of the PV pre-amp. Go figure, I said I was lazy. :-)

So then the answer to your question (for me anyway) is get off your butt and walk to your pre-amp, use the balance control to correct the shift then walk back to your chair and answer honestly the question "Well was that really worth all of the effort".

FYI, the XLO test disc is an out of production disc of high quality and contains, in addition to an out of phase cut, a 'room walk about' where Doug Sax centers a mike in a defined room and walks about the room recording sound at various locations which helps a user understand how the users room sounds or should sound. 
If you are going to get OCD about imaging in your system I highly recommend you get a recording  by Opus 3 called 'depth of image' which contains music recorded simply (microphone wise) and excels in portraying three dimensional imaging.  It is also out of production. 

Have fun.
This thread reminded me of the fact that in all my years I have never used a balance control for anything other than diagnostic purposes. Never to "balance' the output of the music. Never really thought about it, honestly. Must investigate.