Quote Originally Posted by enricoclaudio View Post
You may want to check if the speaker is out of phase (polarity). It could be that at the shop they swap the speaker terminal caps. You can check if the speaker is out of phase with a free app for iOS or Android or just invert speaker cables at the speaker end. In my Sierra Towers and Sierra 2s the Positive (red) terminal is on the right side of the speaker looking from the back.

Check for AudioTools app
Not possible due to the way we test (we test for polarity). This is a strange one but we have been in contact with the customer and we will certainly figure it out after some additional troubleshooting. Customer told Dina that they were working fine at first but then something changed. I am thinking that something may have gotten banged around a bit in transit and possibly a lead came off one of the bottom woofers...