bridged amp

I think what jl35 meant to say is that many bridged amps do NOT work with 4 ohm speakers even if they are compatible with 4 ohms in a stereo configuration. In other words, you may be limited to 8 ohm speakers.

This totally depends on the design, IMO a "bridged" amplifier sounds superior to a single channel amplifier.  

If the amplifier is sturdy enough to handle low impedances bridging it is a non issue. The only issue there is with "bridging" is that the amplifier sees a halved impedance, is if your speakers are 4 ohms the amp sees a 2 Ohm load.  

There are many advantages to bridging a amplifier, for once you get 4 times the power, this because the speaker is now connected to two identical amplifies one end of the voice coil on a positive channel the other end on a negative channel, which is either driven by the negative side of the differential input on the positive channel or by a separate preamplifier channel.  i.e. the negative node in a balanced signal, the preferred way.  

Good Listening 

Peter
 

It says 100 W 8 Ohm and 200 W 8 Ohm bridged.