Right, I was aware of that, I just didn't know that there would be such a dramatic difference between the signal level/voltage and the perceived loudness. Now I know! 
What you hear with your ears(perceived loudness) and what you see on the meters are totally different animals, especially on digital boards. After A/D conversion, you can't get hotter than 0 DBFS because everything is measured from 0 DB Full Scale down. There is no voltage.
So when recording, your number one priority is not what you hear with your ears but what you see on the record level meters. This especially true on multi-tracking. But in your case, you only have a stereo track so the real concern is the balance between all the channels summed to a single track which is exactly the house mix. I'm assuming what you are recording is the FOH stereo mix.
Everything else is coming through strong except 2 channels. You can hear them but not loud enough. Crank up the bass/kick channel fader and eq up 6db or more with all amps off and check level at daw. It should come up and if it does, drop the subs amp levels. What you have is a routing/mix problem so you need to do whatever it takes, switch channels, change levels or whatever.
No on here seems to know your board so if nothing works, check with Roland or a Roland forum. Hope this helps.
