Should I use all RCA inputs on a multi-channel amplifier if I’m making a bridge connection?

Simply put, the word “bridge” in this case means the combination of the amplifier’s output channels.

Example: Using a TS 800x4, which is a 4-channel amplifier, with each channel delivering 200W RMS at 2 Ohms. To make a bridge connection with channels 1 and 2, for example, you must connect the positive wire of the speaker to the positive terminal of channel 1, and the negative wire to the negative terminal of channel 2. In this way, your speaker will receive 400W RMS at 4 Ohms!

Therefore, to ensure the proper operation of these speakers connected in bridge, the RCAs must be connected to their respective inputs — in this case, channels 1 and 2, where our speaker is connected.