I am impressed with the Tak 300B but have not heard the Elrog offering. 15% less power should not be a concern to a 300B tube user “If” they properly matched their speakers from the onset.
If the extra 15% makes a difference, I am of the opinion that you have the wrong speakers to begin with.
If the extra 15% makes a difference, I am of the opinion that you have the wrong speakers to begin with.