This is 'Oozora no Auriga' by Sahashi Toshihiko, from the anime Simoun. I arranged every part (violins 1 and 2, viola, cello, bass and piano) by ear in one week using FinaleNotepad. And I used Magix Audio to play around with the original song. It was fun, but it got really frustrating and tiring by the end of the week. I'm glad it turned out nicely though. p.s. The audio's pretty bad, just beca