Please help me with these string quartets

[mattzart]

I've had these recordings on my computer for years and could never figure out who the composers were. I know it's going to be some real obvious composer and a real obvious string quartet, but I cannot, for the life of me, figure it out.

http://www.zshare.net/audio/5159569fa370ed/
http://www.zshare.net/audio/51595992b39b3b/
http://www.zshare.net/audio/5159620b80de5e/
http://www.zshare.net/audio/51596501587140/

Thanks in advance.

[Christopher RA]

It sounds to me like Haydn, but I don't know which Quartet.  Depending on how determined you are, you might want to listen to all of them to compare.

[Que]

Would be glad to help, but the clips don't play on my computer (Mac).

Q

[Mozart]

The first one is Mozart, I know it I just can't find the piece. I think it is from a serenade...

[Mozart]

Yes! I have found it. It is Mozart's serenade in D (shocking that it's in D, really ) k.136

[FideLeo]

I can hear the first two on my macbook... no the fact is, I only recognise the first two at this moment  
the first one is from the andante movement of Mozart's Divertimento K. 136
the second one is an arrangement of the Prelude to Marc-Antoine Charpentier's Te Deum (the Eurovision theme)
the third doesn't ring a bell at all
the fourth sounds like something by Boccherini, given that characteristic rhythmic pattern in the lower parts