I want to buy the AKG K 601's, are they worth it?

Hey - I own k601s and I really like them - however, they are more suited to classical/jazz/acoustic music than they are to rock and roll. This isn't to say that they fare poorly with rock, its just that they don't have tons of bass impact, they are a pretty well balanced phone. AKG is known for having a sort airy sounding wide soundstage which lends itself well to the classical/jazz/acoustic style. I listen a wide range of music with my k601 and am generally satisfied, but rock isn't where they shine.

The q701, as I understand it (I don't own them) handles the bass a bit better and I believe that in practice they are a little easier to drive than the 601. You can often find the q701 in the used forums here and I think you could get it new on amazon for a bit over 200, maybe about $225?

Not sure about an amp at that price point - I had a fiio e10 and while it could get more out of the k601 than my computer's mini jack output it paled in comparison to my gilmore lite (which it should, the glite is much pricer). The JDS Labs O2+ODAC is a pretty nice unit and it isn't crazy expensive but it does come in well over 100 bucks. Maybe something made by firestone audio would work? The Fubar IV Plus? 

I'd read up on the q701 and see if it would fit your needs - but for rock/pop listening lots of people suggest grados. The AKG headphones need some reasonable power, so if you are looking to upgrade, but not spend a ton on an amp/headphone pairing, it might be sensible to look at other manufacturers. 

Just wanted to add - I'm listening to Jamiroquai right now and I'm totally happy with the bass and the sound from the k601. A favorite track of mine for demoing headphones is Fragile by Yes - again, I'm very pleased with the k601s performance. However, listening to Offspring, I'm just less impressed - they don't sound bad at all - but just not as impressive. Similar with Poundcake by Van Halen - hope this helps!