QUOTE(rosfrog @ Oct 22 2009, 09:46 AM)

He claims that any difference you hear is either A) psychological or B) so tiny that anyone standing more than a foot away won't hear it.
He chuckles at the idea of violinists stressing over every little thing "Oh, I must have this rosin - it will make a better sound' or 'if I get my tailpiece changed, my tone will improve' or 'I want a dark sounding fiddle' or 'can you just recommend a G string that will make a better sound' - his reply is often 'just learn to play the damn thing and stop shopping for stuff'.
I have to say - I largely agree with him!
He is, of course, referring to difference you
hear. I don't have any claim that Goldflex
sounds better than the stuff I threw out, merely that it
feels better. I don't have any expectation that it will improve my playing to listen to in any way but psychological security, but psychological factors are huge. If your shoulder rest (or absence of one) is a set-up that makes you feel as if you are constantly chasing the fiddle around and it keeps dropping off your shoulder then the effect on your playing is huge because you don't feel that sense of security that no, the violin/viola isn't going to shoot across the room if you do a wider vibrato. It almost certainly won't, but you have to feel and believe that it won't and then you will commit. The Goldflex feels 100 times more secure and smooth than the Hindersine, which always felt as if my bow was about to get away from me. Possibly I never used to put enough on and I could have got a good result if I caked on tonnes, but it seemed to make so little difference I ended up hardly using it. The Goldflex went on so easily by comparison. Once on it may well be no better, but you always have to get it on there in the first place, so a rosin that goes on smoothly and easily is high priority for me. I suppose it would be similar to changing the size of my viola to a 15in instrument - it's still a viola, it's still a great viola, but it's not for me and I can't play it.
I'm not sure how much I believe that the different Pirastro ones really do match their individual strings, but since the Obligato would be a suitable rosin for you in any case I'd say you may as well choose that one unless you want to get something cheaper.