This party is so popular!
So just like before, you want the spaghetti recipe yada yada yada... basically, you want to get in to the party.
The first guest arrives, the security guard says "6". The guest goes away to check the answer, but soon returns, saying "3", and is admitted.
The second guest arrives, the security guard looks annoyed and says "1", in a menacing tone. The guest says "9" and is admitted.
The third guest arrives, the security guard says "5" and the guest replies back, "0", and is admitted.
It's the next guest's turn now. The security guard says "2", and to your surprise, the guest attacks him! The guest overpowers the security guard, and tries to enter the party without saying anything! But another security guard appears (from the infinite stock of security guards in the guardroom) and stops him. Abashed, the guest says "2" and is admitted to the party.
So now the original security guard is back on his feet and he's looking angry. Another guest comes up to him and the guard grabs him by the collar. Clearly he's looking to get his revenge on these unruly guests! He snarls, "3", but the guest replies "5" and the security guard is forced to admit him.
It's your turn now. You go up to the door and the security guard says "4". You hope that he'll admit you, but you know that it's pointless to try overpowering him. What do you reply?
As you're standing outside the party waiting for inspiration to strike, you hear music and voices coming from inside the party. Could this be a clue? [Yes]
The track listing is:
Royale With Cheese (Dialogue), Pulp Fiction on Pulp Fiction
20th Century Fox, The Doors on The Best of The Doors
Mr Tambourine Man, The Byrds on American Graffiti (More) - 1979
Out of Space, The Prodigy
Space Oddity, David Bowie on Best of Bowie
Indiana Jones Theme, John Williams on Raiders of the Lost Ark
Space Cowboy, Jamiroquai on The Return of the Space Cowboy
The Galaxy Song, Eric Idle on Eric Idle Sings Monty Python
Girl From Mars, Ash on 1977
Across the Universe, Fiona Apple on Across the Universe
Choose Life, Underworld
Born To Be Wild (With Miss Piggy) Ozzy Osbourne, on Prince Of Darkness (Box Set)
New clue: Decode the message enciphered in these symbols: ↗↑↙↓↘←↑↙↘↘↗↓↗←↙↓↖ (also solved)
Administrative details (not part of the puzzle):
This is the latest instalment in the Party Security series.
Answers in spoiler blocks please.
Where someone proposes a solution that is not the method I'm thinking of, I've decided not to comment on whether the actual answer they've given is correct, because if I do then it provides an additional data point; which changes the puzzle for other people.
The other playlists on the Grooveshark account have nothing to do with this puzzle, neither does the Grooveshark username or the Grooveshark profile pic.
The Pulp Fiction dialogue track is NSFW if your workplace has objections to swearing. All the rest should be fine to play out-loud.