In-ceiling: Am I wasting my money?

Hi everyone:

Bought and moved into a new home. The builder has in-ceiling speakers installed in the living room. There are 5 speakers, but I have no interest in using them for HT -  just for music. They appear to be 8" Monoprice speakers, I have no additional details on them.

For the short term, I'm thinking of picking up a Sonos: Amp since I'm already invested in that ecosystem. I can use that to drive 4 of the speakers by hooking them up in parallel.

Now, here's the big question - I was toying with the idea of picking up a 200 watt/chan McIntosh integrated amp and replacing the Monoprice speakers with four higher quality in-ceiling speakers - perhaps something like the B&O 10" Celestial (BOC106) which are really made by Origin Acoustics (but with prettier covers).

So - am I wasting my money by doing this and I'm better off just sticking with the Sonos Amp and maybe upgrading (or keeping) the speakers to something better but not as expensive? Or... full speed ahead?

Note / extra info: Unfortunately, the layout of the room and the decor in it has ruled out a floor-standing or in-wall system... so I'm trying to keep this to an in-ceiling system. The living room ceiling is about 14' high and flat.

Thanks.