Samsung Epic 4G :: Sound Quality During Calls And Visual Voicemail

Sort of two things which might be related. I've been having call quality issues with this phone since I got it. I thought it sounded very electronic and could hardly stay on the phone. Took it to a Sprint store and they did a soft reset and said they couldn't duplicate the issue. I made some calls, some said it sounded better. As long as I have the volume turned down it seems to be okay. But then it's hard to hear what they are saying. If I turn up the volume it sounds like someone is yelling too loudly too close to a microphone. Like bad speakers rattling or something (especially with "s" sounds).

On my headset which was $100 and worked so well on my old phone (people couldn't even tell I was on a headset) the person on the other side either says it's "okay" or says they can definitely tell I'm distant, to one friend saying it was "awful." When listening to Visual Voice Mail it's awful sound, regardless of the volume. Want to try to get a new phone, but then worried I'll have one of the other issues everyone else is having (WiFi or GPS or whatever).