Hi Riihn
Try this:
- Open the Sonos App > Select More > Select Settings > Select Room Settings > Select the room named for the Beam > Look for Volume Limit > It should read as "off" > If not Select it and move the slider to the right_100%
- Also, if you have an iOS device (or can borrow one) run TruePlay
In truth the Beam is not intended for a very large space. If using the Beam in such an environment adding a Sub has been known to improve the audio especially for voice. I realize a Sub is a substantial investment; but what it does is relieve the Beam from processing the low-end.
If you cannot get the Beam to perform to your satisfaction the only other option (barring some defect) is to purchase the Playbar or Playbase. However, you'll lose all the neat features the Beam offers and forced to use Optical input.
Edit: I see you're using Optical any way so no significant loss of features to go with a Playbar or Playbase. The Playbase will retain Airplay capability.
Let us know how things sort out.
Cheers!Together Everyone Achieves More = T.E.A.M.