Is it Possible??

The higher you go in frequency the more it radiates out towards the front in the direction the speakers are pointed. Standing behind the speakers you are getting almost none of the highest frequency treble. 

Higher frequencies are also very easily absorbed but all kinds of things like carpet, furniture, people, etc. The lower you go in frequency the less of an effect these things have. 

So what we have here is a situation where standing behind the speakers the top end is rolled way off, and outside the room the top end is rolled way off. You like this better. Therefore you like rolled off. 

There are all kinds of things you can do, starting with the obvious, point the speakers away. Turn the tweeters down if they have trim pots for this. Add a resistor if they don't. You can also try going to warmer components but if you really do like it better from behind than in front (and we are still talking speakers mind you) that is pretty drastic and unlikely to be fixed with components. 

Not saying I would do any of these but it is your system not mine. If this is what you like this is how to get it: drape a blanket over em.