I had a problem like that on my Classe Twenty five. Got it used and it had a few nicks and scratches on it. Like you I tried filling them with a sharpie and it didn’t match perfectly, but at lest you didn’t see the stark contrast of the bare metal against the black. It was annoying and I could find the spots when I looked at them, but then Italians that when I stepped back a few feet to the point where it would be looked at from 99% of the time, you really did not notice it much at all. Especially if you did not not where to look for it.
Of course the other thing was that being a high power amp with a lot of heat sinks, the heat had shifted the color of the anidizing on the fins such as the were not longer a perfect color match to the front panel, which had not been subject to the same heat load. So energy I’d i had the front panel refinished it would not
have matched the rest of the amp.
The final solution? Come to grips with the fact that it was a piece of audio gear and not art and as long as it sounded great that’s what really mattered.
And it didn’t hurt to remember that those small visual imperfections saved me several hundred dollars of the used price, allowing me to get a much better sounding amp for my audio bucks, and I would make that traded off any day.