Deleterious effects of bridging ??

Bridging does not result in seeing half the speaker impedance. There is no complete circuit to just the + or - terminal. Bridging puts the outputs of the two amps in series, effectively doubling the available output voltage swing. The same gain setting will result in supplying twice the current to the SAME load, if the amp has the current capability. That results in four times the power. That is why some mention the problem of an inherently low impedance speaker with the additional voltage swing of a bridged amp applied. Often the amp can not supply that much current. That is why 3 to 4 times the power is correctly claimed in a previous post. How much current does your speaker take to drive it to adequate listening levels and what is its nominal impedance? Does your unbridged have high enough voltage output to drive it to that level? Those are the questions. If it doesn't play loud enough and the amp is voltage limiting, then bridging is a possible solution. If it doesn't play loud enough and the amp is current limiting, then you need a higher current supplying amp or a more efficient speaker. Bridging won't help because if the amp is current limiting unbridged, it will just limit at a lower gain setting when bridged. I know, a lot of words, but there are 3 current threads on bridging and a lot of misunderstanding. See BIAMPING under Speakers, for example (it includes bridging). :)