Crystal clear for me - running a ext sound card and a decent headset , a few things to monitor are your cpu's load and heat, CoreTemp is a good free program for this. if you have an on board s/card and your cpu is not up to scratch it maybe a load issue.
Also check drivers for sound card - ensuring updated version - would recommend re-installing anyway.
As Dr Roly mentioned check your bass settings it may be simply that your speaker can't take the bass gain and it's particular heavy during take off / landing , jump to hyper drive.