Recording sounds too high but it's not

Hi, I have a dell laptop (ct55t) which is connected to my berhinger DX626 mixer. Input into the mixer is a denon DN-D6000. I use this to DJ. My recordings were fine but now it sounds as if it is recorded too high like extreme distortion yet, the music sounds like it is at low volume and just distorted. Any ideas on what it could be? I also have Realtek HD audio manager if that matters. I’ve attached a sample

It’s dual-mono, (the channels are identical), and there’s nothing above 7kHz.
If the original is stereo, an anti-phase cancelling-effect could make it mono.
The “HIGH” treble controls on the mixer would be capable of cutting the frequencies above 7kHz …

Hi there and thank you so much. I feel bad but honestly, I’m VERY ignorant on this. So when you say “It’s dual-mono, (the channels are identical), and there’s nothing above 7kHz.” I guess my question is, what do I do or what can I do to correct this? I assume the problem is my mixer and not audactity, right? If so is it just about turning up the treble or? Thanks again for any help, really just need this to go into the mix. THANKS!

Ensure that the cables, (from deck to mixer, & from mixer to computer) have stereo signals:
i.e. at no point are stereo (L R) signals are combined in the cabling.

You didn’t mention how you’re connecting the mixer to the computer,
I can imagine an adapter to do that which will combine the stereo signals into mono and could explain your problems.

If the mixer does not have USB out, it should be connected to line-in on the computer,
or to a gadget which converts a computer USB socket into line-in.