advice on dedicated line

Although the electrician will say you don't need it, I went with 10 gauge wire.
Digital equipment should be on it's own dedicated circuit.
The amp should be on it's own separate dedicated circuit.
I'd go with a third dedicated circuit for the front end (preamp and what ever other gear you have or will obtain some day as long as it's not digital gear.
The three individual 20 amp circuit breakers should be placed in the service box on the side with the least nosiest appliances.
Personally, I like the Porter-Port that Albert Porter sells here on Audiogon. There are other outlet options available for more money and/or less money.
I'm sure other members will have some additional good ideas.

"Do I want two dedicated lines--one for the amplifier and one for everything else? So 2 20 amp circuits with 10 gauge wire?"

If you have a small system and as long as your amp is not a monster, you can get by with 2 dedicated 20 amp lines. The current draw from a CDP, DAC, Sonos, or preamp is very low. Good outlets are important and so is surge protection. Later on, you'll probably want to get a power conditioner.

Thanks, all. This is very helpful. My amp is 50wpc, so I am thinking 2 lines. Lowrider57 (or anyone else who cares to answer): would I get a separate surge protector for each outlet, and can you recommend a good, moderately priced one? Also any more suggestions for good outlets? Elizabeth, I have another question on ground wires, but that will have to wait a bit because I am heading out now to go audition some speakers. :). Thanks again, everyone, for your excellent guidance. M.

Lak has it covered nicely.
The only add I would offer is that if your system is quite a distance from your service box, you may consider having them run a 50 or 60 amp sub-panel, positioned somewhere nearer to your system and then all your individual circuits would run out of the sub-panel.