bad amp or speaker

yesterday i noticed that the music isnt sounding right. i cant tell whats wrong, but it doesnt sound like it used to. i think the highs arent there anymore, or as much. i used to have the treble set at +2, now its at the max of +12 and it still sounds low and kinda muffled sounding. is it possible for a broken amp to only put out certain frequencies or is it just a bad speaker? i thought about testing other speakers, but i dont have any.

Check the ohms in the speakers, no reading means bye-bye voicecoil

how do i check? and the speakers work, they just dont sound good. theyre 2ways... is it possible for the woofer to work and not the tweeter?