Connecting DJM 700 to Macbook to record

Hi all,

I have two CDJ850 which I connected via USB to my Macbook Pro and control them with rekordbox Performance mode with a CDJXDJ Aggregator Device for Mac.

So far so good. Now I want to record these mixes though.

For that I plugged in a Chinch to aux cable to REC of the DJM700 and then connected that to a cheap 20€ external USB sound card. However, this is not recognised in rekordbox and when i record via Audacity the audio track totally overloads.

1. Is there anything I can do here differently so that I somehow can record with a good quality? I didn't find a way to lower the volume enough in the system settings.

2. I googled a bit and found that I could also use a MIDI to USB Interface/adapter. However, I couldn't find out if I then can record my mixed (ideally directly in rekordbox). Example MIDI to USB Can someone confirm that I could use such a device for recording? I'm not interested in controlling the DJM but only the recording.