question for Luxman L-590AX owners

All I can say is I love the sound of the 507ux and the complete lack of buzzing. :)

Here is another such product, about $150 :

https://avahifi.com/products/humdinger-dc-line-blocker


Of course, more expensive solutions are to use a balanced power transformer, which are themselves subject to mechanical hum without enhanced circuitry. :-)

I do want to point out that yes, any lights with little wall warts, especially those with built in dimmers, may introduce DC.  The best way to diagnose this is to turn off everything in the house except your amp and see if it goes away.  Then start flipping breakers back on until the hum reappears.

What happens is that these devices only take power from one side of the AC line, but not the other. This lack of symmetrical power draw causes DC to appear, and then the mechanical hum.

Best,

Erik

This often happens to any amp's transformer when DC enters the line. Did you recently move a PC, or add a dimmer switch somewhere??