crackling computer speakers

please help me out here . this problem is so annoying and disturbing our music learning experience i have an old dell desktop assigned for softmozart software , it was doing well till lately , when turning he speakers volume up you hear crackling , so painful for my ears . i feel this is not good when one want sot play the games , the sounds fromt he computer is so yakee . Now could this be a software problem or i should trash my speakers and buy new ones ?? those came with the computer years ago , my new computer is a laptop and i know we won't be playing if kids have to wait for mama to connect the laptop to the keyboard so i really like having this old desktop assigned forsoftmozart .
come the most important question , pleas help me out so i don't spend endless nights on amazon trying to guess what best to buy , what best to buy that could replace my speakers , so we can continue enjoying learnign with softmozart ?? i know we can spend thousands on speakers , but do we need that ?? and i don't want to buy the cheapest available that would not give good sound , so please i need a link xxx

problem solved thanks to wonderful Manda xxx God i cannot believe i was doing it wrong all this time . All i needed to do is to chance the sound output to my yamaha instead of computer speakers . now kids can really enjoy and learn from their games xx