Yes, you are correct it is indeed an old spruce. I will take another closer look at the mushrooms on my next stroll to be certain. Since the colours don't quite match to be an fomitopsis pinicola but maybe they are really old ones.
I know that the picture is not sharp enough to determine the mushroom with certainty. I decreased the quality so it won't take too long to load. (The original picture was taken in .raw, but I think pictures that big will crash this whole post ;) )

Thank you for your insight! If my path crosses younger fungi I will try your recommendation!

Yours: >^.<