Poor Quality Sound

Folks

I have recently taking the plunge in to the world of Sonos.

I really like the concept and it is very easy to set up with my NAS system (Synology ds212j)

I have a the following
Bridge
Player 3
Player 5 On loan as a test

Denon CD Player , with 2 Speakers

However I do have a issue with the overall quality of the Player's

I ripped a CD "Bat out of Hell" to FLAC
With the Denon and Player 3 in the same room (Denon 2 speakers in each corner ) and Player 3 in the middle.

I found the Player 3 did not really fill the room with sound , even though both systems where using the same volume.

Turning up the volume just makes it more tinny.

I then tried the same with Player 5 and found the same results.

I am doing something wrong ?

Or should I be looking at using SonOS Connect:amp and hooking up the Denon Speakers.

Any thoughts would be very welcome.