[schof]

You can essentially guess the problem from the title, I have a Yamaha receiver, and my laptop 3.5mm hooked to it through RCA. I am listening to some Monster Turbine Pro's through the 1/4 inch connection on the front of my receiver. In short, it sounds like poop.
 
If I plug the turbines just through the 3.5mm port on the laptop, I get much better sound, which I find a bit strange frankly. So what's the deal? Could it be that my receiver has an equalizer that is clashing with the one I am using on the lappy? I have the receiver on flat, so I expected this to not be an issue.
 
In a related, but different question, in this setup, I get some buzz. Not a ton, but enough that I can hear it on the quiets on some tracks.
 
Thanks for you help!
 
(Also, this is my first post, so I may be putting this in the wrong forum, or asking a question that everyone knows the answer to, if so, sorry.)

 

[Joe Bloggs]

If the headphone out of your Yamaha is driven by the speaker amp through high-ohm resistors as described here
http://www.head-fi.org/t/572819/power-headphones-with-reciever
 
It would have low damping factor driving low impedance IEMs and depending on how much the impedance of your IEM varies with frequency, modified frequency response as if the receiver had a built in EQ.
 
There was a circuit that supposedly combats the problem way back in the day
http://www.head-fi.org/t/21851/the-impeder-less-than-10-ohms-output-from-any-piece-of-gear
 
But I'm not sure whether it actually helps or makes things worse, strictly technically speaking.  I think it lessens the effect of an uneven IEM impedance curve on the frequency response, but as for damping factor, I don't really understand how it's calculated so can't comment.

 

[bixby]

Part of it could be that you are amping the signal twice.  Once when coming out of the headphone out on the computer and again with the Yamaha.  The computer has a relatively cheap headphone circuit as does the Yamaha unless it is about 30 years old or so.  Try adjusting the volume control on your player software to see if that helps.  Sometimes setting the computer volume to about 70-80% of max gives the best signal to noise ratio and no clipping.  Then adjust your Yamaha volume to see if it improves.  
 
Another way to test the headphone circuit of the Yamaha is to run headphone out of an ipod or other portable device into it and see how it sounds.  I had a Sony receiver that I gave to my son that had a horrendous headphone out.  It is just hit or miss on most receivers made in the last 20 years or so.
 
EDIT:  Just tried it with my Westone UM3X and Macbook hp out.  Not bad sounding but definitely worse when run via a mini cable to my portable amp.  If you really want better sound you may need to go with an outboard dac then to the Yamaha.

 

[schof]

Thanks guys, I will experiment a little more, and post back what I find. 
 
I appreciate your comments.