The bridging wiring technique to take the positive from the receiver's right channel and connecting to the positive terminal on the speaker, then take the negative from the receiver left channel to the speakers negative terminal. The speaker is 8 ohm so the load should drop to 4ohms.
That is not bridging, nor is connecting the outputs of the two channels together which is what I believe Simon was addressing.
I suspect that your NAD, like most amplifiers or receivers that do not have balanced outputs, has the negative output terminals of both channels connected together internally. Therefore the connections you are proposing would make no difference compared to connecting the speaker to the output terminals of one channel.
Bridging as properly defined (for an amplifier having unbalanced outputs) involves connecting the speaker between the two positive output terminals, with no connection to the negative terminals, and having one channel of the amplifier process a signal that is inverted with respect to the one being processed by the other channel. That will usually result in a large increase in the amount of power that can be delivered into an 8 ohm load, because as a rough approximation it would double the range of output voltages that the amplifier can provide. However, it is not usually practicable to do that unless the amplifier design specifically provides for it, and according to the manual
your NAD does not.