[shigzeo]

you should not hear enhancement from a line out, merely a better signal to send to an amp. in fact, a good headphone out from a portable should be very like a line out when used with an amplifier as the amp will then unload the headphone output.

many lineouts are not proper and still pass through amp circuts. but, then externally amping them or feeding them from a resistor cable will get them to be less loaded