reducing the Limiter setting seemed to make it sound just a touch better.
If it changes anything then the signal is hot enough to trigger it. This is not good quality wise.
by the way, I don't know what the difference is between dB and dBFS
dB is a ratio, to put it in simplified terms. dBFS is used to measure digital signals, it's level relative to full scale. In the case of 24 bits, full scale is 0 dB to -144 dB. If it's hotter than 0 dB, it cannot be assigned a number, it's beyond the range, an error. It's like dividing by zero in a way. So you never allow digital signal to go beyond 0 dB. Or even approach it, because whatever your meters show, there are fast transients that are hotter. You want see them, as the meters aren't fast enough, but they are there and will cause clipping. Usually they make the sound kind of harsh.
For analog (like for the inputs of your mixer), dBu is used. That's the level of signal relative to some reference voltage. 0 dBu is exactly that reference voltage (0.775 V). It doesn't mean clipping unless that's the maximum your mixer can handle. +6 dBu will be twice that voltage. Pro gear should handle more than that, maybe up to +20 dBu (close to 8 V), but that differs.
Your Axe is capable of outputting up to +20 dBu, your mixer - I don't know, but it should be able to handle that, your wireless most probably will start clipping at +10 or so. So if your Axe outputs +12, that'll be some 3 V hitting your input mixer, and after passing the converter it'll become -5 dBFS or so, and, assuming everything is set to unity gain, it'll output 3V, and will cause your wireless to clip.
Otherwise a dB is a dB is a dB.
