Singer sounds lower than ear level, help raise it

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.

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

My speakers are NHT M100. It has a 25cm driver at the bottom, 2.5cm tweeter in middle and a 16cm driver on top.
I've tried sitting it on the floor- even lower.
Will try tilting the speakers.
Ya my equipments are in the center of the speakers- will try moving them away.
Maybe my room & set up kills a lot of the critical high frequency info leaving nothing but the mid-range, how to fix this?
Try raising your speakers until the mid-range driver is ear height - the midrange is already on top of all the drivers.

Thanks for all the great advices.
1)Listening at particularly low volume levels - will try with higher volume.

2)Dead tweeters - they're working.

3)Room acoustics - can't really fix it, my room is sort of a U shape room, need to do too much to fix the problem.

4)A mismatch between amplifier output impedance and the speaker's variation of impedance as a function of frequency. Blue circle BC2 class a.

6)Listening off axis or with improper toe-in, as was pointed out - that means by changing the toe-in we can fix the problem? Definitely will try this.
Thanks

I tried to near my speakers to 6 feet apart from current 8 feet, the vocals raised a bit. Will try 7 feet and 9 feet later.
My listening chair is 9 or 10 feet from the speakers.
I'm more keen to try tilting the speakers up and see what will happens, still trying to find something to slot under the front spikes.
Will update result.
Thank you for all the great advices.

I'm using RCA. No more budget to change interconnect. When i have budget will change the speakers to high efficient one.