Hi Alex, although I agree about the usefulness of a DI box, it's not for the reason you describe. The X50 has low impedance unbalanced outputs, of 1.1Kohm or 550ohms for L/MONO. So impedance matching isn't much of a problem because the line level low impedance output is sufficient to drive the mic/line inputs of mixers. The problem is when there's a long cable run to the PA where a long snake is used, making balanced signaling preferred to get lower interference due to common-mode rejection with the balanced inputs on the PA mixer.Alex_G wrote:Keererw, you may be confused about how a DI box works. The signal path from the x-50 is a line level, high impedance singal. A DI box receives that and outputs a balanced, low impedance signal to the PA (the guts are almost identical to an AC transformer). These are informally referred to as instrument level and mic level signals, respectively.
A line level instrument should always be run through a DI. Always. (You don't need a fancy, active DI, a $25 passive one will work great).
The ground levels between stage AC power circuits and front of house PA power circuits can be significantly different due to the varying distance of the conductors to the common grounding point. Some outlets may also have improper grounding or share the circuit with heavy inductive loads that can transmit noise over ground.