There's no such thing as a 6X. It you're using the TLS 5X, it's a 8 ohm box, and your powered mixer puts out 270 watts into each channel at that impedence. My band uses a pair of 5X speakers, driven by 200 watts/channel. It's enough for small/medium indoor gigs and for rehearsal, but outdoors the overload protection circuits in the powered mixer kick in and shut down one or both amp channels. Your band's backline is probably just too loud for the volume you're going to be able to get from those speakers, driving them with that particular powered mixer. If the mixer allows you to connect a separate, more powerful, power amp, that's one option. Another would be to just turn down the backline to a level where the PA can keep up. You'll probably still have more than adequate volume unless you're in a larger or very crowded venue. We've found, a bit to our surprise, that most audiences and venues appreciate that we play at a more moderate volume than many other bands; louder sometimes drives away more people than it attracts.
