I've not used that site myself. Some of my students do. I do not know anyone who has had a problem with it, BUT you probably should be aware that if you're providing financial information to a bunch of Russians who are in Russia.
Not the safest group of people to give your credit card number to.
Better to do single-use CCNs if you feel you need to use that site.
Also, even Russia isn't sure if allofmp3 is legal.