Hate to resurrect this thread but I have a very similar problem with my mx300 that I got recently. My problem is much simpler, The output is incredibly faint, I need to use an amp with max volume to hear anything, so the card is doing it's thing but the output is virtually non existent on any channel. This happens in any of my machines I put the card into (Abit Kt7a, or 4coredual sata2, or an old 440bx motherboard) in windows 98. Looking at the card I don't see any physical problems, the main large cap seems ok. I also tried all version of the drivers for 98. One thing that is strange is that on the headphone output (out2) there is a constant low level noise (hdd and fan interference) I can hear.