I have been using the QSC K10’s (the original ones) for several years now. I find them quite amazing, with plenty of connectivity and sound sculpting options on board. I do have a Behringer 12 inch sub that I like to bring in for outdoor venues, but virtually all indoor shows I have plenty of bass from the K10’s as long as you don’t want a full real band volume!
As with all speakers, there is a limit to how loud you can take them before they lose their linearity, but for events that aren’t playing to teenagers and twentysomethings, the QSC’s do the job.
The only caveat I would say is, do you want to have your sound nice and loud right next to you and immediately in front, but with a steep drop off as you move away, or do you want a sound that is very even throughout the venue? If you want low volume everywhere, the ‘stick and sub’ Bose Compact type systems will do that better than the K10’s. Me, I still like at least a decent volume while I play (I’m from a live band background!) but want the sound to drop off before it gets to the tables. Others may prefer a low volume both by yourself AND the audience. Strokes for folks!
Full disclosure, I put my speakers up slightly behind and either side of me, so they are both backline (monitors) AND PA. If you already use in-ears or a monitor, your mileage may vary. But with an EV N/Dym microphone, I really never get feedback until I’m ear-splittingly loud, so that’s not a factor. But how strongly you sing may influence that.
If small traditional speakers are what you are comfortable with, I can’t recommend the K10’s too highly.
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An arranger is just a tool. What matters is what you build with it..!