Being honestly curious, do android or iOS phones offer audio quality/signal comparable to standalone headphone amps expensive Senneheiser headphones are designed to perform best with? Disclosure: I also own $500 Senneheiser headphones, but use my Bose Bluetooth ones for my phone.
It depends to a great degree on the volume and impedance of headphones. HD-25s perform quite well at normal volume for music that doesn't have tons of transients for phones with decent DACs.
But it's something you have to actively look for in phones.
