An instrument whose players can, unlike tuba players, actually keep time. Originally designed as an improvement on the trumpet, the trombone turned out to be an improvement on all other instruments as well. A single trombonist can, and will outplay many small string ensembles. For every time a trombonist hits fortissimo, a man gets a hard on somewhere, and three women lose their virginity...twice. Also considered by many to have magical properties.
No, there is nothing wrong with your recording equipment's balance, we have a trombone in the ensemble.