I've recorded two clips with the cell phone. One with bass guitar through Axe-Fx (just In1 -> Out1), the other with the Synth block (one voice, sine wave, some freq. between 100 and 200 Hz). I think it's especially noticeable with the sine wave, as the distortion changes with the volume. It sounds like a filter opening/closing, emphasizing overtones. Given it's a sine wave, I guess overtones should be absent or very weak, so I attribute them to the distortion.
I played several notes on the bass and switched through frequencies to rule out any resonances of the speaker/cabinet.
I've attached a zip file with the two m4a files if anyone is interested.
I hope Thomann will understand the issue and can make sure they don't send me another one.
On the upside: I tried it on Tuesday in rehearsal and was very pleased, although I didn't tweak any patches and could not focus on the sound. Just plugged in and played with the band (and the candidate for the vacant drummer position).
That said, older patches I tweaked on my FBT 12ma sounded quite different, not in a good way. Patches I created from scratch at home (with near fields) translated well and sounded quite nice. So I'd like to have this monitor but without the distortion
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
It's not noticeable in rehearsal room though, with the increased volume and everyone else playing and talking. I did not do the synth block test though.
Now contacting Thomann.