Yes, tried pulling speakers out, even used it as motivation to move my whole family room around (although I didn't mention my true motive to the better half), to no great avail.
These just sound lifeless to me. Sound is good, not great. Lacking in bass, boring kids, decent highs. I enjoy HT to above average satisfaction, but musically, very uninspiring.
You've ruled out most everything other than the speakers themselves – speaker location, equalization (at least what correction Yamaha provides with its room eq system), and you have a powerful enough amplifier.
It's time to start listening to other speakers. Don't rush. It may take some time before you know what you like. Then again, because you have been listening critically to your present speakers, you may find what you like quickly.
The Ascends you mentioned have a fairly flat frequency response. That may sound brighter than what you now have, but I prefer to think of them as neutral speakers.
Klipsch speakers (there are too many models for me to know them well) can provide another step up in brightness. Many don't like their sound, including me, but I'm not buying speakers, you are. The Klipsch speakers I've heard in the past all tended to have a megaphone-like tinny sound. Other people seem to like them. So find out what you like.
I had earlier mentioned the Philharmonitor or the Salk SongSurround I. They are similar in price and sound quality to the Ascend Sierra 1.
It might also be worthwhile to mention where you are located. People at AH often do offer auditions to people here who ask. I'm in Maryland, near Washington.
Good luck with your search.