Microphone Ground Loop Buzz

[Yasashii]

I have a ground loop problem at my house. Probably caused by... not actually having a ground. All the sockets in my house only have the positive and negative cables. I know it's not OK, but I can't do anything about it (since it's my parents' house).

So, whenever I connect a microphone to my computer or, in fact, any other input device in my house that's plugged into the wall, I hear a loud 60Hz buzzing noise. I know for a fact that it is caused by the ground loop as when I connect it to my netbook, when it's running on battery only, it goes away.

My netbook isn't my main computer, though, and it's been an issue when using in-game voice communication, when I want to record something and not have it sound terrible and when I want to use voice recognition software.

So, in an attempt to get around this problem I went and bought a ground noise isolator. This kind, to be specific:

 

I think it's just a big lump of metal that acts as a makeshift ground to soak up the noise. It works fine when I connect it to something like my stereo or headphones (as in sound gets through), but when I connect it between my mic and my sound card, the mic doesn't work. I can't figure out why.

My mic is a standard desk one. I use cinch-to-3.5mm-jack adapters on each side of the isolator to connect it to my sound card and mic.

Does anyone know why it doesn't work and how I can make it work, if at all possible?
Is there any other cheapo workaround that I can use to eliminate the buzzing?

[SSL]

What microphone is it and how are you connecting it?

[Yasashii]

8 minutes ago, Yasashii said:

My mic is a standard desk one. I use cinch-to-3.5mm-jack adapters on each side of the isolator to connect it to my sound card and mic.

 

[SSL]

That tells me next to nothing. I can only assume you're wiring it up wrong, but since you didn't actually tell me how you're doing it, I can't say for sure.

[Yasashii]

OK, so the mic is a cheap Logitech desk mic that looks like this (don't know the actual model number):



It has a 3.5mm jack plug.

I connected the female cinch plugs to a cinch-to-female-jack adapter that looks like this:



and plugged the microphone jack into it.

I connected the male cinch plugs to an adapter that looks like this:



And plugged that into the sound card.