Yup, polarities multi-checked. Haven't tried a different mic, will try borrowing one but since the passenger seat tunes fine it's a long shot.
Just curious, has anybody tried a Premium E90 with just aftermarket amps and speakers and compared it with the MS8 in the loop? I installed both at the same time and never got to do the piecewise comparison.
I was quite happy with the stock sound (with L7 disabled) but wanted more bass, dynamics and clarity, which I got, but arguably more attributable to the better amps and speakers. This came at the expense of a soundstage stumbling around like a freshman's vision at his first beer party and an echoing Bluetooth.
Since the Premium already has time alignment and I don't fancy L7, the only real advantage is the flexibility in crossovers frequencies & slopes, but from experience those parameters (at least within reasonable limit) have a far less profound influence than all the other tuning problems introduced by the MS8. Any comments?