What you are hearing are the normal limitations of a mono loudspeaker in a unit that is intended for background listening. Increasing the bitrate won't improve things.
To my ears, the BeoSound 3 has a good sound, for those occasions where I want to have something playing in the background. I use it for audio books, for which it is absolutely perfect.
You may consider the surface it is standing on - a wood cabinet will resonate, adding depth perception to the sound. Don't aim it at glass surfaces or other hard surfaces - and that's it.