Dynamat would work, sounds like overkill, but maybe not so with audiophiles?
Much cheaper would be strips of insulating tape(splicing tape which is like a thick rubber tape), but if you already have the dynamat, sure.
Always worth the effort to eliminate even the smallest likelihood of risk with electrical work. Like what if the box fell from your hands to the floor and a solder joint breaks. Or someone accidentally steps on the box...
And I don't see a fuse, any shorting will result in some part burning before opening, or mains breaker tripping. Sorry, just a possible picture of the worst case scenario.
Solder joints look ok from what I can see, have seen worse.