sky boxes always have good tuners in though, if your only getting 50% on the sky box you'll probably get alot less on the s9, although i dont own 1 so cant comment on tuner quality, but if there anything like the rest of the boxes, the signal will be weaker than the sky box, but atleast your somewhere near, so it can be tweaked to get better the signal you need, ideally you should be aiming for as close to the 90's as possible!

On my S9 i'm sitting at about 84% intensity and 75% Signal Quality. I don't have the luxury of tweaking this as i live in a ground floor apartment.

50/50 seems quite low and even my old Sly HD+ box was 90%+ on one and about 70-80% on the other.