Steep volume curve on channel faders on DDJ-SR (very low volume up to 7-8)

Hi, am relatively new to mixing and recently picked up a DDJ-SR controller. I have found that when using the channel faders / mixer sliders, I have barely audible volume from a channel, until ramping up the slider to around the 7/8 out of 10 level. Audio is barely audible from around 5 downwards, then the curve from 8-10 seems incredibly steep. i.e when mixing or recording a mix i'll generally need to have my secondary track / outgoing track at around 8 or 9, for any of it to be audible, when the other channel is at full volume (10).

Is this normal? I feel like I should be able to at the very least pick up some of the channel when the slider is at around 4-8, but find myself having to have a channel at 7+ constantly even if i want that channel's track to be "in the background".
 
FYI I use a pair of logitech laptop/computer speakers as my audio output, with the RCA outputs hooked up to the speakers' subwoofer unit via a RCA - Aux cable. The two speakers connect to the sub via RCA cables, and are powered by mains. The sub connects to another volume control dial which I have at around 50% while mixing. Could this be down to my speaker setup, a calibration issue, or is this normal functionality for this controller?

Appreciate any support / feedback in advance.