Dedicated line w/ upgraded parts or power cond?

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.

I would start by adding dedicated power line. Actually 2 -3 if possible. One for amp/pre, one for digital. As Elizabeth stated, your existing line may serve as a dedicated.

Theres no way to tell until you try it.

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.

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