Haven’t tried it as a summing mixer for a drum machine yet, for the sole reason that the A4 is my only piece of sound-making gear I have at the moment! Drum summing is exactly what I’m going to do with the Boss in the future, when I get a Tanzbär. Drums through the Boss, the stereo output of the Boss through some nice compressor, then the whole thing to another mixer (which actually might be another Boss, I haven’t decided yet) where the rest of the music is coming from.
Overall assessment is very nice indeed! The demos I posted don’t showcase THAT well how nice it can sound, that particular loop had a bassline and a hihat loop that didn’t particularly benefit from the EQ or overdrive.
Personally,I love that overdrive sounds. The kick and the synth riff sound exactly like I want a mixer overdrive to sound.