I just purchased a Numark USB Turntable from Amazon and am quite excited to convert all of my vinyl to MP3s. However, I have one question: with 2 of these turntables, am I able to play "dummy records" that play MP3s straight off of my computer? I would like to do some DJing, but I don't want to carry all of my vinyl around with me. Just 2 blank records which can play anything would be ideal. I've heard about this, but I don't have any details or knowledge. Thanks for your help!