Nominally, a TruePlay adjustment would take care of that, if you have an iOS device that can run it.

Were it me, I would place it nearer to the couch, rather than all the way in the corner. But I’d also use speaker stands, to place the Era 300s at ear level, as designed by most home theater audio codecs. 

I'd try them in various spots, the corner probably, with the ones you have I'd as most likely for the second one. 

Depending on the direction the chair faces and what percentage of your viewing is from there maybe try behind it too.

 Make temp stands and fool about before wall mounting.