Couple of basics to check:
1. on the 404 make sure your mix button is not fully counter-clockwise. Somewhere between 12 and 5 on the dial is good for playback. If thats not problem then...
2. remove the 404, use your phone or mp3 player go directly into monitors, play music, if volume ok go to next step.
3. hook 404 back up, repeat step 2 but plug player into 404 this time. if problem now then its the 404. If not then problem is further upstream, possibly some setting in daw.
4. How's the volume using headphones into the 404, if thats good, then there's a pretty good chance the settings in your daw are ok.
hope this helps somewhat. If this doesn't help you need to provide more info as to how you have everything hooked up.