I Can recommend Proel Wedge WD12 -or some other Active coaxial stage monitors. I use 2 in a stereo setup, link to PA - The coax is very good reg. to avoid feedback - it Sounds wonderful, i paid just about 300$ a pcs
I Can recommend active 12" coax stagemonitor - i use 2 in a stereo setup and it sounds awesome - very loud and almost no feedback (+ a very reasonable investment)
Use The aux in (The back of The amplifi150) and The mains out from The fx100 - it works fine, sounds a little different than The Sound in the 150 alone
With The fx100 i get The best Sound (from The amplifi150) when i connect it to The aux - in The back of The 150 and from The mains stereo out of The fx100 - it Sounds nice