So I'm currently using an ipod touch with akg q701 and right now i'm thinking about either upgrading my sound player or my head phones.
I'm wondering at what point the sound quality is limited by your player rather than your headphones?
There is the volume issue where some players simply cannot provide enough voltage or current to a headphone.
There is the issue with noise either due to output impedance or improper damping.
There may be issues with grounding or other sources of noise such as EMI especially from portable devices.
Lastly there is the issue with what kind of out the amp section utilizes such as what OP Amp or what tube.
Unless you experience multiple of the above listed conditions I suggest going with a new headphone. Seeing that you have the Q701 I suggestion one of the following or if you can try them all.
1.) AKG K550 ( darker sounding than the Q701 )
2.) ATH-M50 ( a solid and affordable headphone, great bass extension, built well, and pretty neutral sounding )
3.) HE-500 ( excellent sound quality for the price, quick, good bass extension, more comfortable than the LCD products )
I'd say that with a decent quality player (no $10 wally-world MP3 players) particularly one with LOD capability (such as an iPod) and a portable amp, the point at which the source is a real issue is rather far away.
If you don't know, an LOD allows you to bypass the internal amp of a device to avoid double-amping the signal with an external amp. Available for Apple products in the form of everything from $10 adapters to extremely expensive models with silver cables (usually overkill for beginner's rigs)
Welcome to Head-Fi. Sorry about your wallet.