Before you change out equipment, it might help to know that early side wall reflections are interpreted by the ear as harshness. So if your speakers are near the walls, its worth toeing them in a bit, in fact maybe so much that the center of the tweeter is firing such that the two tweeters cross in front of the listening position. Alternatively you could put absorption material on the side walls.
A sub (or subs) could help too. The ear has a built in tone control; if bass is lacking the system will sound tilted towards the highs. If there is too much bass the system could sound muffled.
A single sub can be hard to place due to standing waves in the room, which can cause the bass to be cancelled at the listening position. In most rooms, below about 80Hz the bass is entirely reverberant due to 80Hz having a wavelength of 14 feet (the lower the frequency the longer the wavelength). You ear needs the entire waveform to pass by it to know its there and a few more iterations to know the note itself. By this time, at 80Hz and below the bass has bounced all over the room.
The advantage of this is you don't need stereo bass reproduction below 80Hz or so. 80Hz is sort of the magic frequency because below it you'll have no problem getting a sub to blend and don't have to keep it near the main speakers at all to make it work. Above 80Hz the sub can attract attention to itself so then it will need to be aligned with the main speakers.
Here's a tip: try angling the sub so its output bounces off a side wall. This will help minimize standing waves in the room. The more subs you have up to four, the easier this is to do. If you were paying attention, you may have picked up on the fact that the subs likely work best if placed asymmetrically.
