qgyy2000,
Yes, I was too unkind and too critical with my dismissal of the problem of channel balance.
I have to apologize for that.
And yes, many stereo recordings will have some cancellations of some signals when you just do a simple Mono combine of the signal (L+R).
But if there are such electrical cancellations in the L+R of the recording, then when you have perfectly balanced signals, amps, and loudspeakers, those L and R signals will also cancel acoustically.
And then there are pan pots, phase reversers, and other trick tools in recording and production techniques.
Not all is perfect.
I used to be very careful about signal balance.
I would monitor the L and R channels on an oscilloscope XY display.
You can learn a lot about what different recording techniques are like (results).
I found out about that when I listened to the music and compared it to the XY display.
Many recordings have mono-like equal amplitude and equal phase of L and R signals,
much more than you might expect. If you have an XY scope, you can see the upward 45 degree slope line (and with very little width to that line).
Then you put on another recording, and the XY display 'blooms' with many signals appearing everywhere within what looks more like a scribbled filled-in circle. You can easily find some classical recordings like this, but other recordings like some Jazz ones.
Our 2 ears and our brain have very powerful analysis capability.
. . . But then I lost the use of one ear.
Now, with just one ear, I found out that when you walk across a line that is perpendicular to the line from speaker to speaker, you hear lots of cancellations, like a variable comb filter as you walk the line.
Now, with one ear, I often just use a mono-block tube amp, and a 2-way loudspeaker.
I only apply either just the L signal from the CD player to the amp, or just the R signal to the amp.
There are no L R cancellations when I only use L 'or' R, versus combining L+R.
I plan on building a switch and matrix to take the CD L and R outputs, and give the following:
Left only; Left and -6dB of R; Left and - 3dB of R; L+R; R and -3dB of L; R and -6dB of L;
and R only.
That way, I can hear both the L and R channels on a mono-block amp and single 2-way loudspeaker, but without the cancellation of a simple L+R mono mix that is a problem of some recordings.