The rated power output at 105 watts is for 2 channels driven, so it will be less than that if all channels are driven. Your LSIM 703 speakers have 88db sensitivity and recommended amp power of 20 to 200 watts.
However, none of those stats really help to answer your question. Whether your set-up will sound better with additional amplification power depends on a lot of things. Such as the size and acoustic properties of your room, the volume that you listen at, whether you listen to music / movies / multi channel / stereo. As well as your expectations and your ears!
There are a few other threads on here where some people, me included, have found that even quite powerful and expensive AVR's can sometimes be out performed for stereo music listening, by power amps, even the very inexpensive pro audio ones.
If you are asking the question, it suggests that you are not completely satisfied with how your set-up sounds. The only way that you will know for sure if it will sound better with more power is to try it. Can you borrow / home demo / or trial a power amp in some way (sale or return?).