It took us far too much of the first set to sort out the appropriate settings on both the sub and the tops - too many options everywhere - but by about 20 mins in @Silvia Bluejay was beginning to get less disgusted with the basic sound and starting to apply the right EQ to make improvements.
I thought the sub was strangely sensitive (on its own volume control) to an exact sweet spot for best resuts, but we weren't being helped by either the room (very lively) or the band layout - we had the tops on either side of the band and the sub on the floor dead centre, but further forward than I'd have preferred due to a partition getting in the way.
By set #2 Silvie had it completely under control and the sound was fine, certainly far better than with just the CP8s on their own. They're great units and I really rate them for confined spaces, but Silvie never tires of pointing out that they're really intended for use as floor wedges and sound awful compared to our more serious PA kit.
As an audio experience, and judged purely for that, the Citronic sub + 2xQSC CP8s rig was actually a bit meh and of course that's exactly what I expected. Now factor in the portability and form factor in a badly-designed boozer with a tricky load-in and it all makes sense. I'm delighted that we have that rig ... we won't use it often but we'll use it where we need it, and that will probably be a dozen times a year.