audio quality and volume in android vs apple

hello,
i have an ipod nano and when i play music using my headphones (Sennheiser Momentum 2 wired) the volume is way higher than my oneplus 6t (same audio file) (also the volume is higher in my brothers iphone x but still not as good as my ipod) , why is that? and can i make my oneplus like or close to my ipod?

thanks for the helpers