New Amp Hook up with mixer

D-I -XLR output

He all need a bit of help here.
I now have a Fishman loudbox amp. (Mini)
1st question. Is it best to use the D-I out on the back of the amp
and run that cable to the mixer and run the Main out of the mixer to a P.a or a set of powered speakers?

This is just for a mic and guitar being used in the mixer.

This is how I had it riged up…I ran the 2 main out from the mixer to the mic in and the instrument in on the amp…and had my guitar plus a mic plugged in the mixer…and it sounded bad.
Useing a ProFX8 mixer.
Thanks ahead of time