Sylvania SRT2227W

I just purchased a used Sylvania 27" SRT2227W w/ Composite Video Input. The problem is with the sound. It works, but it is very distorted. There is a like a high pitched buzz behind the sound. It makes it sound warbly and hard to hear. It makes the sound sort of electronic/robotic. HOWEVER, when you get to certain volume levels, this goes away. Well, really only one volume, and it is pretty loud. In addition, it sounds like the volume has been like boosted up or something, meaning I get it about halfway up the volume scale and it it really really loud - I can't imagine putting it up all the way. Well, thanks for your replies - Tristan