SMSL A300 Stereo Amplifier Review

[Toku]

“So depending on what speaker you throw at it, the treble may be a bit bright or subdued.”

Can someone tell me how does "load dependency" affect the speaker?

I think what you are concerned about is the circled part of the graph.
It is true that the measurement results show that in the case of an 8Ω load, the level increases from around 15kHz. However, the average person's ears can hardly hear frequencies above 17kHz, so this has very little effect on sound quality. My ears can't hear even 15KHz anymore.
The effect on sound quality is far greater due to differences in the characteristics of individual speakers.