I know there have probably been threads on this topic before, but I would like to discuss it further. I am a downstream player, and I have been told to use upstream air while playing and that it doesn't matter. I know many great jazz trumpet players have been upstream players, but I know of equally great ones that used downstream. My whole life, I have never been upstream. I was just curious as to what the rest of you thought. Downstream? Upstream? Does it really matter?