Sansa Clip Zip with Rockbox & Sennheiser MX 880

I know what equalizer is. But I’m not sure I understood you correctly. Translation problems. I’m not US/UK. I understood that by using equalizer on player I will equalize earphones so they change their sound characteristic. What I mean is that after playing at eq for a long time earphones will not play at default settings same as before. 

I think I starded to thinking too much after I read some pages about equalizing earphones like How to equalize earphones. I don’t get this page.