Do you mean a computer sound card? Yes, I have a crappy one, but it is definitely not the source of the problem. I tried connecting my turntable DIRECTLY to my computer speakers (well, through the preamp, of course), without the help of my computer. No matter how and through what I connect it, it gives off that hum. It is a hundred percent turntable-caused problem.Unfortunately, I have not yet tried using a differet cartridge. I do want to buy a new one, and I was thinking, maybe I should go and buy it now, even before I fix the problem? I will purchase a brand new turntable sometime anyway, so I will need one. For now, I could use it on my old turntable.
Let me think...
And on weekends I am going to post the results of the test.