Will changing speakers only, be of any improvement ?
Yes, generally, however to improve your sound you have to go for high grade units not just based on price.
The thing is this, Better quality speakers usually have better dynamic range = more clarity. = better listening, unfortunately this = lots of money
Add an amplifier and you get boosted sound, more volume (if that’s your thing).
Firstly, I would try adding acoustic dampening behind your existing speakers and you will improve the level of sound performance.
In theory, your existing speakers should sound better and it should improve the clarity as the speaker is not impaired by background effects or sound bounce from behind the cone.
Don't just shove the acoustic dampening in behind the speaker. It should be shaped to suit the speaker cone so the speaker projects the sound.
This is a low cost option that should improving your listening pleasure.