Singer sounds lower than ear level, help raise it

This has far more to do with the electronics than speakers.

Whatever you do, don't try tilting the speakers a couple of degrees. Tilting them back a bit might actually shift the perceived center of the soundstage upwards, which would be horrible -- especially as that is exactly what you're looking for. Or, crazy of crazies, you could try tilting them forward -- which with my speakers actually seems to shift the whole soundstage about two feet upwards. Daffy, but true. But, like I said, I really don't recommend trying it, even if it does work, because it is totally not cost effective. Besides, what are you going to do if it doesn't work, just put'em back?!? That's just crazy talk.....

i thought we just need to add something under the front spikes to make the speakers' front higher.

Sounds to me as though you have the wrong amplifier paired with the speakers and the resulting performance of the speakers is not balanced. (mismatch of amplifier and speakers)

Probably wrong amplifier - speakers match. My power amps are mono 75watt class a.
Permissible input of the speakers - (Maximum) 450W/ch.
But right now i have no intention to change equipments. Need a cheap way to raise the focus point.