I am using an HP 15-r264dx laptop with windows 8.1. It has Realtek sound. When I plug in my headphones the recorded sound with Audacity is much better than when I listen with the laptop speakers and record from the Stereo mix input with a youtube video playing. My guess is that the low impedance speakers are loading small value capacitors that narrow the bandwidth of the audio that goes into the stereo mix that is put to Audacity recording. My headphone is about 100 ohms per channel and I am guessing the built-in speakers are about 8 ohms each per channel. The laptop has DTS audio settings. The recorded sound quality is also much better when I plug in the headphone output to the line-in of my amplifier to monitor recording. Also, to clarify more, using the speakers to monitor recording with stereo mix creates a recording similar to the acoustics of the built in speakers. Using the built-in microphone to record created no difference with the headphone plugged in or not other than the feedback when I unplugged the headphone with software playthrough. With my paranoia as a schizophrenic, I am thinking the electronics of the computer is recording what I hear acoustically.
I think you’re overthinking this. If either the playback system or the record system has software to “enhance” the experience, that effect will be part of the recording or the playback (or both). Windows Enhanced Services is legendary for “helping” you make a recording in Windows, whether you want it to or not. Enhanced Services does OK with spoken word, but it hates music.
Also, if you’re recording internet sound, some systems send the network sound all the way out to the analog amplifiers…and bring it all the way back in, picking up “enhancements” all along the way. Those recordings may not sound like anything else on earth.
If you have very different quality depending on your sound pathway, you may have caught your machine with its pants down; putting in effects in the wrong place.
No, I don’t think it has anything to do with your 100 ohm headphones. The built-in speakers in your laptop are never going to sound very good. You can’t put very much gut-moving bass in a one-inch speaker, no matter how well it’s made.
All this is assuming your show was created properly. There was a recent poster with stereo damage in his show. Under certain playback conditions his show would vanish or sound very odd. It’s possible you have that, too.