Dedicated line w/ upgraded parts or power cond?

Theres no way to tell until you try it.

First: is you current AC line separate from others?
Or is the refrigerator on it?
If it is free of any appliances, and only say an incandescent lamp on it. then that is pretty much 80% of what a separte line will do.
If the outlet you use is the 'first in line' of a chain of outlets. better. If it is the last in a line, that is bad.
If it is both first and nothing else on it. the you HAVE a dedicated line. Just not one you paid a lot of money for.

I have such a line for my equipment.

The powerconditioner:
Do you want greater clarity? tigher bass? Yes to coonditioner.
Lack bass? no to conditioner.

Lack bass AND want greater clarity.. Jeez My problem. Took a lot to have both.

Powercords. the can of worms. Wayyyy too many possible powercords.
The one I recommend for amp if you want a little more solid bass is an AC9 pangea. two meter length at least.
Others good Shunyata Venom. I have all Pangea in my setup.
And two power conditioners.

ZD's answer is spot on. As far as I have been able to determine, this business is completely empirical. One can provide some general guidance, which Elizabeth has done, but the whole power supply thing is a case of how your unique AC is supplied to your listening room, and how the AC through your lines and outlets interact with your particular equipment. New, cryo treated outlets can be an inexpensive place to start the experiment. I use the Audio Magic outlets, which for a modest investment gave me a substantial return. I have also recently invested heavily (painfully, one might say) in VH Audio AirSine Power Chords. These PC's took my Cary amps to an entirely different level. But there is no such thing as a universally applicable "best PC for every application" so this is also a guessing game. The cable company can be an asset here. I also strongly suggest you e-mail Chris at VH Audio. He is a straight-shooter, and carries high bang for the buck stuff. Not just his own, but also gear from other vendors. As for dedicated lines, I will be running that experiment early next year. When my Cary amps pull enough current to dim the lights, I think I can safely conclude that there is work to be done in this area.

Dedicated line with a good outlet. I have two with Furutech outlets.

i can say in my case dedicated line was by far better than any power conditioner i used. in fact once i put the direct line in i found the power conditioner i was using actually hindered the sound, dynamics seemed to be restricted.

the other consideration, you can put a direct line in at a fraction of the cost of a power conditioner.