[NoxNoctum]

This won't work right? Or will sound terrible?

 

[MindsMirror]

A guitar won't work correctly plugged directly into a headphone/speaker amp input, due to the guitar being high impedance. You could use a preamp to connect the guitar to the amp, and it would sound very clean, even more so than a guitar amp on clean settings. I think an effects pedal should be able to work as a preamp, if you play electric guitar you should at least have a few of those. Try one and see how it sounds. You would probably want to use an overdrive pedal, and some reverb, otherwise I don't think it would sound very good pumping a clean electric guitar signal straight into your ears.

 

[madbass10]

Guitars sound absolutely horrible through any audio gear meant to be high fidelity. Guitar amps are meant to color the sound a lot. There's usually more distortion going on than you think, even in clean tones. Amps usually give you a lot of compression too, so playing feels better when the little inconsistencies in your playing are glossed over.
 
I do a lot of my playing through headphones using a digital modeler and sometimes my pedalboard in front. In a lot of ways it's much nicer than using an amp, even if it doesn't feel as fun. I use a PodXT right now and have no complaints.