If you are careful, you can use masking tape to fix the dented tweeter. Gently apply the tape to the dent, and gently pull it
away. When the dent pops out, peel, rather than pull, the tape off. It is possible that the speakers need to be re-broken in if they sat so long. Adhesives and other components i the speaker may have stiffened. Putting some hours on the speakers could help.
Also consider improving your source. Even a low-priced USB DAC (there are thousands of them out there) will be a step up over the audio output jack of your laptop. And if you are using cheap cables, consider a small investment in some entry level audiophile cables and speaker wires (Morrow, Audioquest, Pangea, etc.). They also can make a difference, IME.
The B&Ws will usually sound better with help from a subwoofer, used in moderation, as will most speakers, IMHO.
IIRC, the Rotel has some adjustability of audio parameters, like bass and treble controls. You can use these to smooth out the sound a bit. But, heck, if you prefer one of the surround music modes like Neo6, go for it.
Finally, a little time spent positioning the speakers could help the sound as well, even if the processor is set correctly for the various speaker distances.