What brand of laptop are you using? If it is a Windows based OS then the sound coming out of it is almost always going to be noisy. This is because of the power noise that latches onto the DAC which is basically a noise isolation issue. Most external DAC devices bypass most of the noisy components by using either USB or SPDIF sources. Without my external DAC I can hear all sorts of noise. I can hear when I move the mouse around, type on the keyboard, or turn up or down the fan speeds. PC listening without a good DAC is unbearable.
Many MAC based OS Laptops actually have much quieter audio signal paths which I can only guess is because of better isolation.
There are people out there who must question the audio from a portable device like an iPod. These people will claim that the sound out of their portable device should always be inferior in some way to another setup they have. They often make this claim without giving any measurements. The DAC inside most iPod devices is actually really good. This goes for iPads as well. If you turn the volume all of the way up you hear silence which is one indicator of a low noise DAC. Now I cannot speak of the jitter coming out of the DAC inside my iPod, but I know for a fact that if you install lossless, AAC, or even 196kbs MP3 files and the source music is well mastered, one is going to be hard pressed to hear major flaws in the output from the iPod's DAC. The quality DAC design inside your iPod is good enough to make your PC listening experience sound poor. This should be a good thing because as I mentioned audio listening via PC is almost always noisy without an external DAC.
If your issue is more about volume, low end kick, and distortion, then try adjusting the various volume settings. This includes adjusting the volume controls within Sound and Audio Devices for Windows bases systems. You will want to adjust the volume on your player as well whether it is iTunes or some other player. If you still cannot reach the volume levels you want you are most likely going to need to amplify the signal.
After you play around with your sound settings try downloading Foobar2000 and see if that helps at all. It is a player that a ton of us use because it has a ton of customization as well as taking up very little RAM when playing.
The ATH-PRO700MK2 is pretty easy to drive. They are rated at 106 dB /mW and 38 Ohms. Just about anything should drive those to really loud levels even your PC.
