Might be a obvious question.
Have you tried to lowering the treble, does it help or will it mess things up more?
I found this and few measuring chart.
There seems to be ~3-5db lift on treble range with Vocal, Dynamic and Classic modes.
You could the try the Monitor mode for more flat response.
On every chart, there is a tiny boost on 2-5k range. That might be the peak you notice that is raping ur ears. Would hate it also and would EQ it out.
If situation does not improve. Different speaker might be in order.