If you are talking 128 kbps MP3, it doesn't matter where you play it.
If you are talking 320 kbps MP3 (minimal compression) you may hear a difference.
Good original materials don't need enhancement. What may make a difference from a PC/laptop is noise shielding, PC/laptops tend to be noisy suckers that can interfere with audio, BUT interference only affect analog, so if you keep things digital and use an external DAC/amplifier is the way to go for golden ears.
An external DAC/amp also helps with the amplifier stage, which is often weak in ALL portable devices.
Don't go the deep end. If you can't hear it, what does it matter.