PC not differentiating Left/Right channel properly

Driver settings

Your audio driver should have settings window similar to this:

One can choose headphones and two channel speakers as separate options because these devices provide significantly different stereo experience given the same input. It's all about…

Sound perception

When you think about how humans perceive the sound, you may notice that:

• Most sounds that come from your right go in fact to both ears. The sound has to travel around the head to reach the left ear; that takes some time and alters the sound a little.
• The situation when you hear with the right ear only is when the sound source is located very close to your right ear and relatively quiet, like whispering straight to the ear.

• There are several mechanisms your brain uses to locate the sound:

  1. Sounds that are not very distant, coming from a side are heard by one ear louder than by the other – like the said whispering. This mechanism fails for distant sounds because their amplitudes drop insignificantly. 10 cm from the right ear may be 30 cm from the left ear, which is three times more. 1 km from the right one is 1 km from the left one, the difference is insignificant.
  2. A change in a sound coming from a side is heard by one ear earlier than by the other. The more rapid the change the better. A distant thunder may be perceived to be to the left or right while (1) fails.
  3. Sounds that are more melodic than noisy can be located thanks to the phase shift of the wave between the ears. This spectacularly fails with high pitch sounds; their wavelength is shorter than the distance between the ears and your brain gets confused. Have you ever heard a cricket sound coming from "everywhere"? If you get with your head close enough to let (1) to work, you can locate the cricket.
  4. Former methods can tell left from right but not other directions. Fortunately every sound is altered by the shape of your auricles and your head. This makes the difference between the sounds in front of you and behind you. The problem is your brain must be familiar with the sound because a sound coming from the front may be perceived exactly like some slightly different sound coming from the back (and vice versa).
  5. Every move of your head changes your perception a little and helps your brain build the acoustic image of your surroundings. Many animals move their ears to achieve that. Few times I have experienced the illusion where unfamiliar sound was located by (4) to be (e.g.) in front of me as long as my head was still. I moved my head and the perceived sound "jumped" to the back, the illusion broke and I couldn't make it reappear.

Having this in mind we can see that…

Headphones and speakers have different abilities

When your computer generates the sound (say: from FPS game) and when it is aware you are using headphones, it can take advantage of (1-4) to make the sound more realistic. Virtual reality gears also use (5). Having strictly separated channels to the user's right and left ear makes all sound tricks possible.

The setup with two speakers is limited, e.g. it's hard to simulate whispering to the ear when every sound from every speaker goes to both ears. There are tricks that use interference to enhance the perception but it's always something different than headphones. Of course to successfully use those tricks on you the audio driver should know you are using speakers.

That's why the driver needs to know what kind of device is connected.

Stereo recordings

I think the vast majority of stereo recordings is made in a way that for the best reception the left channel is supposed to be heard from the left and the right channel is supposed to be heard from the right. It may seem obvious and not worth mentioning, unless you realize it's something different than "the left channel is supposed to go to the left ear only…".

When your computer is aware (i.e. it is told) there are speakers connected (and there are no sound effects), it just sends the recording left channel to the left speaker, right to the right, the only thing to do is applying volume. You hear "left" sounds with your both ears but you can tell they come from the left thanks to the mechanisms described above.

On the other hand, when your computer is aware there are headphones connected, the driver rebuilds the sound to give you the impression that "left" sounds come from the left, not only to your left ear. The left channel goes to the right ear also but with reduced volume to induce (1), with a delay to induce (2), with phase shift to induce (3) and with other modifications to induce (4). The details of this rebuilding process depend on the audio card, its vendor, the driver itself – this makes some cards better than the others.

I used to have a setup where my speakers and headphones were connected to the same socket (via mini jack splitter). I switched my audio driver option few times a day depending on the device I was using at the moment, because every mismatch seemed unnatural to me. My brother hardly ever noticed the difference.

Your specific problem

I guess your audio driver is told there are headphones connected (or the socket you connect them to is dedicated to headphones only), that's why you hear "little high" and "little low" in both left and right headphones. Still, the direction of sound should be clearly recognizable, the experience should be similar to listening the recording on speakers.

It looks like your Xiaomi doesn't care whether there are speakers or headphones connected. It passes the channels without mixing because it's the easiest thing to do. When it comes to the music, this is the right thing with speakers. My old Samsung also does this the easy way which I find awful with headphones, especially during songs that separate channels as significantly as Bohemian Rhapsody does. Hearing the singing with only one ear seems unnatural and gives me headache. Fortunately I have good Bluetooth headphones, they have an option to rebuild the sound on their own.

It seems to me you got used to your Xiaomi behavior (which I find wrong) and expect it from your PC. You may even think some part of Bohemian Rhapsody magic comes from the channels being separated in the way you like. There's nothing wrong with that, I have no intention to "fix" your thinking, I can even imagine the Queen might intended this "ear separation" which is achievable only with headphones and without mixing.

Anyway, now you know where the difference comes from.

Solution

To make your sound card pass the channels without mixing them, tell the driver you have two speakers connected. I have little experience with sound cards and their drivers but I guess if the socket you use is dedicated to headphones only (it may be front panel socket) then this option may or may not apply. In case it didn't, you should connect your headphones to the socket where speakers may be connected (like in the rear).

You should also remember that some sound effects and enhancements (e.g. surround sound) may distort stereo image. Their impact may be different with speakers and headphones. Check if you have them disabled.