I google searched and found the following comments from other people regarding the Luxman M-120A getting hot (in quotes):
"The Luxman M-120A uses a heat-pipe arrangement for output device cooling. In order for it to function, it has to get warm.
Luxman had some heat design issues that seem to show up years after the units were built. It might be some components are running near their limits or other components going out of spec causing resistors to drop more voltage than design.
In any case, if you are confident in opening the unit and looking around I would recommend it. Just look for charred, darkened boards and such to see if your unit might need some TLC or repair. If all is good then make sure the unit has the right amount of air circulation to allow proper designed cooling to avoid any issues.
Some gear gets warm/hot by design. Knowing what is too hot is hard to tell for each unit but if you think it is too hot, have it looked at and voltages checked.
Another consideration is what speakers are you driving with it? A lot of amps tend to run hot when driving "difficult" loads (low impedence speakers or multiple pairs of speakers)".
[end of research].
It is my opinion that maybe you should have your amplifier checked. This seems reasonable to prevent further damage due to continued usage. This is specially true if the unit is more than 10 (?) years old.
I also suggest you call a Luxman dealer, or distributor, and ask them for their opinion.
I own the Luxman L-590ax class A integrated amplifier. It gets hot because it is a class A amplifier. I keep it well ventilated and it works fine.
"The Luxman M-120A uses a heat-pipe arrangement for output device cooling. In order for it to function, it has to get warm.
Luxman had some heat design issues that seem to show up years after the units were built. It might be some components are running near their limits or other components going out of spec causing resistors to drop more voltage than design.
In any case, if you are confident in opening the unit and looking around I would recommend it. Just look for charred, darkened boards and such to see if your unit might need some TLC or repair. If all is good then make sure the unit has the right amount of air circulation to allow proper designed cooling to avoid any issues.
Some gear gets warm/hot by design. Knowing what is too hot is hard to tell for each unit but if you think it is too hot, have it looked at and voltages checked.
Another consideration is what speakers are you driving with it? A lot of amps tend to run hot when driving "difficult" loads (low impedence speakers or multiple pairs of speakers)".
[end of research].
It is my opinion that maybe you should have your amplifier checked. This seems reasonable to prevent further damage due to continued usage. This is specially true if the unit is more than 10 (?) years old.
I also suggest you call a Luxman dealer, or distributor, and ask them for their opinion.
I own the Luxman L-590ax class A integrated amplifier. It gets hot because it is a class A amplifier. I keep it well ventilated and it works fine.