Pairing Magicos with a sub

I found lots of discussion around subwoofers, but in most of rhe cases they are about pairing a sub with speakers with limited bass extension. I am curious does anyone have experience pairing Magico S5 or similar speakers, which go quite low, with a sub(s). I have the S5 and I am wondering if I add a sub can I improve the dynamic when listening at low levels. Although the S5 is pure joy to listen at higher volume levels, often I feel to tired for this and prefer enjoying not very loud music. This is the only reason I started to think adding a sub. After some research my potential choice is the Rel G1 Mark II. 
I will appreciate your thoughts on this.