Hmmm, from what I understand, the concept of using a stereo amp in bridged-mono mode is really no different than a true monoblock. They both use "antiphase summing" where one amp board pushes while the other amp board pulls. They both have to use push-pull transistors arrays where one set of transistors is pushing the positive side of the waveform and the other set pulls for the negative side of the waveform. However, stereo amps cannot normally support low impedance loads. For example, DNA 500 is a stereo amp that supports 500 watts into 8 ohms or 900 watts into 4 ohms. When bridged, I suspect that you do not want to run a load under 8 ohms.
The Luxman is designed with higher current, but again the impedance capability is halved when bridged. However, they support 1 ohm loads in stereo and 2 ohm loads bridged.
A dedicated monoblock usually has a power supply design that can adequately support low impedance loads (such as 4 ohm or lower). Based on what I can find, that Clayton M300 is a true monoblock.
The Luxman is designed with higher current, but again the impedance capability is halved when bridged. However, they support 1 ohm loads in stereo and 2 ohm loads bridged.
A dedicated monoblock usually has a power supply design that can adequately support low impedance loads (such as 4 ohm or lower). Based on what I can find, that Clayton M300 is a true monoblock.