Hi there I need your help!
I have been using Audacity for a while now to record vinyl mixes, through connecting the mixer (Numrak M6 USB) to my laptop using a USB connection. Only lately I have been having issues with the recording.
The volume that comes out of the speakers are sounding the same for channel 1 and channel 2. Although on Audacity the volume for the recording are showing significantly different (left channel recording at -30bb opposed to right channel recording at -6db).
I have attached a photo showing the audacity setting on my laptop:
https://www.dropbox.com/s/8837qzd3vi6cgwd/recording%20audacity%20issue.JPG?dl=0
and a video showing the overall set up and the recording process:
https://www.dropbox.com/s/33yhjhbpdcuew69/recording%20issue%2016-4-2020.mp4?dl=0
I am wondering if the issue is from audacity or my mixer?
That would be problem with your mixer. Audacity is only “capturing” whatever it’s getting over the USB bus.
But it’s very weird because the analog-to-digital converter should share a connection with the main/master mixer output.
Thans DvDdoug,
It is really weird! I would really like to know where the problem is coming from, so I can decide what to do 
I checked a lot of things:
- I changed the USB connection;
- I used Ableton instead of Audacity;
- I unplugged and re-plugged everything.
Any other suggestions for checks I could do ?
Any other suggestions for checks I could do ?
I think your mixer needs to be repaired or replaced. 
…But, it’s hard to understand how it’s possible to get a mix out of the analog outputs and an un-mixed signal out of the USB port. It’s suppose there could be two different internal mixing amplifiers/circuits but I don’t know why they’d build it that way.
P.S
Your mixer has 3 analog outputs - Master, Booth, and Record (plus the balanced master). Check all 3 of those. If one of those doesn’t work it would confirm that the mixer is broken. (I’m guessing the Record-output is the same as the USB.)