While I 100% believe in using whatever audio for creative purposes on an artistic level. On Audiotool, I'd stick to just instrumentals and can the acapellas. It's not about protecting yourself, it's about keeping the site fair and free for everyone. If you remember from before, the staff completely revoked everyone's ability to upload and use samples, and a big reason for that was Acapellas since they're very very obvious.
The only real reason its a problem to sample now is because record companies invest tons of money into making artists famous. So they need their piece of the pie wherever it is. I know copyright law is there to protect creators theoretically, but let's be real. Big copyright law only matters because the industry wants to protect it's money, and not for any actual artistic reason. I wholly subscribe to the creative commons ideal of transforming and reproducing art in any way with credit.
I enjoy the roots of HipHop, and 90s rap and electronic music which was heavily defined by underground pirate radio and sampling drums, vocalists, and funk and soul records. It's really stupid and pisses me off that we have so many laws now because I think music should be free and open. It stifles artists to put arbitrary limitations on what they can put in their art.