poor sound quality with beats audio

I have an HP Envy Beats laptop 13" (about 2 years old)....not sure of the exact model details....

For over a year now the sound quality has been noticably poorer than when i first bought it. Thats both through the laptop speakers and through earphones, from various sources like iTunes, youtube etc....

Ive tried everything i can with regards to windows sound properties and also the beats program, but it still stays the same.

Any ideas on what i can do??

Also the sound still plays through the laptop speakers when i plug in my earphones which is another annoyance.

Any help would be greatly appreciated!

Thanks!