Use a single USB cable between MODX's "USB TO HOST" port and your laptop. Install the latest "Yamaha Steinberg USB Drivers" for your laptop's OS from the MODX download page. The USA page is: https://usa.yamaha.com/products/music_production/synthesizers/modx/downloads.html

You would navigate to your region's page.

On your computer, tell the system sounds to utilize the MODX sound output. This will have all system sounds on your computer route out to your MODX's headphones assuming the USB gain is turned up.

You can use anything to play backing tracks. A DAW is not necessary. If using a DAW - then you would need to setup MODX as the output output device in the DAW configuration, load the backing track in the DAW to an audio track assigned to MODX's audio output (Main L/R).

This is the best way.

Using a headphone output of your laptop (if it has one) is not recommended due to quality and also problems with level matching.

Thank you!