Not sure it’s possible to do that with a fully balanced differential amp such as the XA30.5, at least without risking damage to the amp. And even if it were possible I don’t think it would provide any benefit.
In the case of an amp having unbalanced outputs, where the voltage on the negative output terminal of each channel is usually at ground potential (zero volts), bridging would potentially double the maximum voltage that can be applied across the speaker load. In the case of an amp having balanced outputs, such as the XA30.5, both the negative output terminal of each channel and the positive output terminal of each channel are putting out full amplitude signals, that are opposite in polarity with respect to each other. That would still be the case if the speaker is connected between a terminal of one channel and a terminal of the other channel having the opposite polarity (assuming the same input is provided to both channels), resulting in little or no change in power capability compared to normal stereo operation. Assuming, that is, that damage to the amp does not occur and that its self-protection mechanisms aren’t triggered, and I’m not certain that either of those possibilities wouldn’t occur.
Regards,
-- Al
