Scary... I wouldn't be close (...much less in front of it!). Do you add the highs from the piezo to the highs of the mid-bass or do you have a band-pass xover on the mid-bass? (Do you have?) Attenuation of the piezo with a cap in series, also? Because you might have about 10dBs of a step difference there, unless you make a (xover) smooth transition. Regards