bloke wrote:When I played this piece a couple of years ago, there were two tubas on stage and one up in a balcony...How many "possible" (according to the score) tuba players could theoretically be involved in a performance of this work?
Well, Wikipedia shows that the score calls for 4 tubas in the orchestra on stage, 2 tubas in "Brass Choir 1" and 4 ophicleides in "Brass Choir 4"...those parts are, naturally, usually covered by tubas.
So - 10 tubas for a full-forces performance of the Requiem.
EDIT: After looking carefully at the available scores at IMLSP, it doesn't appear that there are any parts for 4 tubas in the "on stage" orchestra (another example of why one shouldn't immediately trust info on Wikipedia). Granted, there are three movements left out at IMSLP (Rex tremendae, Domine Jesu Christe, and Sanctus), but I'm relatively sure those three are written for small-scale forces. The score shows parts for Tuba I-II in Choir 1 and Tuba III-VI in Choir 4. Tuba I-II are always in unison (can be covered by one player). Tuba III-VI, always shown on one line, represent two parts - mostly octaves, but some back-and-forth rhythmic stuff as well...these 4 parts can be covered by two players. Therefore, the entire piece can be covered by 3 players.
Sorry for the misinformation.