Speakers sound best facing wall????

Should I complain? - After months of tweaking and testing various components, I found my perfect sound. It really sounds beautiful and genuine (I listen only to classical; and authenticity is paramount), and the stereo image is there, when speakers are turned away from me, facing the wall at 135 degrees. I am looking at their backs when listening,

So, I am really happy. Or should I? With that very odd speaker position, something must be very wrong somewhere???

Ever since I took on my old hobby again (it had been in neglect for 30 years), bought 2 different solid state amplifiers (a powerful and very well balanced Sony TA-FA3ES, and a lower quality Technics), 2 different cd players (Arcam and Cyrus), 2 different sets of loudspeakers (Heybrook Heylo and Tannoy Revolution), a Velodyne subwoofer, a power conditioner (Belkin) and 2 sets of shielded IEC power cables and interconnects, I have been battling a problem:

*****an ear-piercing treble*****

No matter how low I would adjust the treble on my amplifier, and no matter the combination of amps, cd players, speakers etc., their position, my armchair's position, that problem was still there... until I turned the speakers away from me.

Room acoustics? - Well, all my equipment is in my living room, which has a normal height, and an odd, asymetrical shape. See plan. The house is made of timber, and the walls are painted plaster panels, with 2 dozens glass covered pictures in wooden frames. The room is carpeted, and slightly emptier than an average living room (3 armchairs, 2 wooden cabinets and audio rack). The wall which the speakers are facing has a curtain. The speakers are 130cm / 4ft away from the wall.

If not the room acoustics, what may be causing the ear-piercing treble when speakers are turned towards me? - Dirty power that the power conditioner cannot cope with? Faulty tweeters (on 2 different sets of speakers???)? Should I worry, since I have my perfect sound with the speakers facing the wall? - Any advice appreciated!