Pathos Heritage

I just got my Pathos Heritage for my home in the USA, but I am experiencing something I have never seen before; when I first plugged it in with the volume at half it sounded pretty low, kind of scary low for a 80Wpc amp running Avantgrade Duo Mezzo XD speakers or Tannoy Kensington.

After running it for about 100hrs the loudness dramatically increased.

I have owned and own quite a few amplifiers and never seen something like this before.

‘this is REW’s measurements at the first few hours

and here after about a hundred