Lookin for a wee bit of advice.

I have got my hands on 3 active speakers from Thomann (The Box 108A, 110A & MA120MKII). These all have options for Line or Mic inputs.

I intend to use them as monitors at gigs, running acoustic guitars, Bass Guitar, vocals and an electric drumkit through a small mixing desk and then onto the monitors.

Whilst playing about with them tonight I noticed that the 'Mic' setting is much much louder than using the 'Line in' setting. Why is this?

At the moment I have them set for 'Line in' as everything is coming from a mixer. Is it safe, for my equipment, to set the monitors to Mic?

If anyone could answer this and expand on any comments I would be much obliged.

Cheers,

Richard