the impedance of headphones range from 30 ohms to 600 ohms .. and with that much difference, it's safe to say 10,000 ohms from a receiver is either causing something electrically to switch (or the input impedance of the receivers are a flat-out lie).
the average person isnt going to know the impedance of the input for the mp3 recorder.
and if your onboard soundcard has anything dedicated to headphones (like higher impedance mainly) the extra voltage could ruin the mp3 recorder by overdriving the input.
what is the input of the mp3 recorder?
i'm thinking.. if the mp3 recorder has an input with a headphone jack, it is probably for a microphone.
lots of microphones are 60 ohms - 150 ohms
that is probably enough for a headphone output jack IF the headphone output isnt a 'dedicated headphone amplifier'
because those are ment to output higher voltages into higher resistance (ohms)
it's funny that you mention it though..
because my soundcard would drive a pair of 30 ohm headphones.. but it is also supposed to drive 10,000 - 20,000 ohm inputs of a receiver or amplifier.
again..
either the input resistance of the receiver is a lie, or it is designed to work with a very very low input level.
the soundcard is rated at 2 volts output.. but it doesnt say for what impedance.
the headphone output of the soundcard might be the logical choice.. but if your soundcard adds HRTF to the audio because it is ment to be coming from a speaker an inch away from your ear drum.. that can cause the audio to have a funny sound when not wearing headphones.
the reverb is very very small, and you might not notice it.
but it could lead to misleading listening fatigue.
since some mp3 recorders have a speaker.. you can place that speaker up to your ear at low volume and make use of any HRTF effects.
or
you could plug in some headphones into the mp3 recorder and also make benefit of the HRTF effects.
if you are gonna be listening through a speaker on the mp3 recorder with the volume way up.. it probably isnt gonna kill you to have the HRTF effects.
and there is no guarantee that there are any HRTF effects.
just make sure there is nothing about 'headphone amplifier'
and i really dont think they make any onboard soundcards with a headphone amplifier anyways.
but that advice is only supposed to make you do a simple check so you dont ruin the mp3 recorder after the 1st, 2nd, or 3rd time you plug it in.
higher ohms for the input of the mp3 recorder will help save the life of the onboard soundcard.
the soundcard amplifier wont struggle until the ohms get low and the electricity is pouring and pouring out of it.
meaning.. it is better to connect something with a higher input impedance and use the volume without keeping it on maximum to drive whatever is plugged in.
too much volume being on maximum can cause the amplifier to fail.
keeping the amplifier constantly 'running' because the electricity is being poured out faster than it can gather up some electricity can also cause the amplifier to fail.
my guess.. try the headphone output first, and if the output on the mp3 recorder is low.. then try the line-out.
it is supposed to be a high ohm and low ohm issue.. but some of these soundcards have output jacks that will do both.
line-out outputs can be slower and more relaxed.
headphone outputs have to be faster and more vicious to keep up with the lower resistance.
an amplifier views low resistance like running as fast as you can while leaning forward as much as you can without falling.
high resistance would be like trying to run as fast as you can while leaning backwards.. the person will slow down if they lean back far enough.
and the person could also run faster if leaning forward (but the movement on the legs would probably cause damage when the legs are forced to move like climbing stairs.. the weight of the persons body will fall on unnatural parts of the knee joint... meaning, you will probably stand with weak legs when you are 70 years old)
low ohm inputs dont need the extra power that high ohm outputs need.
the low ohm situation requires stability.. the high ohm output requires more voltage.
these can be done together or seperately.
examples of it being done together are car amplifiers.. you see the wattage double everytime the impedance gets cut in half.
8 ohms = 100 watts
4 ohms = 200 watts
2 ohms = 400 watts
1 ohms = 800 watts
as you can see, as the ohms gets higher, more electricity is needed to bring the wattage back up.
this should be all for you.
have fun enjoying your portable music