Can't yell you if it is inverting or not but the sure wat to tell is if you switch the leads to the amp and whichever way it sounds better is the way to keep it at. After that it matters not a jot if it inverts because it is now the way it is supposed to be and it can't do any harm. Hope this helps as many moons ago I had ancient Quad preamps which inverted an once corrected sounded great (for the time)!!
