I keep my Kismet amp on 24-7, my Hegel preamp as well. When I’m not going to be listening to music during most of the week. (I mostly listen Thursday through Sunday) I detach one of the XLRs. no buzz.
IMO, if you’re spending thousands of dollars on components and interconnects, you shouldn’t have to tolerate any type of noise or buzz. Isn’t that why you’re spending those big bucks in the first place? I’m sure kingbr could do the same (as what you’re doing), but I support his not wanting to, and I’m doing my best to try and help him out.
For over 3 decades I was a Chief Engineer for numerous radio stations. I learned the hard way how to eliminate hums and buzzes, of all kinds. Try connecting hundreds of pieces of broadcast equipment together (both balanced and unbalanced analog) in 14 studios (in one building), and see how many buzzes and hums you encounter (spoiler alert; there will be a lot). And if I do say so myself, there was rarely ever a buzz or hum I couldn't get rid of.
If it were me, there’s no way I would tolerate a buzz, when spending thousands on home audio equipment. From looking at the manuals on line for the Sim and Mac that are involved here, the XLR outputs are of low impedance, and the balanced XLR inputs are of high impedance - exactly the way it should be, but that’s a very simple way of looking at this, as there’s so much more that goes into a decently designed piece of audio equipment. I’m having a hard time understanding why these two pieces of equipment can’t be happy (with no buzzing) playing nicely together (such technical talk).