1. Dedicated lines are a good investment and will provide a benefit in terms of minimizing power anomalies from other users and less noise from things such as light ballasts, switching power supplies (computers) and household motors on the same circuit. Two of them are not overkill (four plugs will fill up quickly). Dimmers should be avoided like the plague on audio/TV circuits.
2. Quality wall receptacles range from ten to two hundred dollars a pop. Some have stated no difference between, say, a Hubbell specification grade and a Wattgate "audio grade" while others swear by the order of magnitude improvement the big buck receptacle ushers in. Your on your own.
3. What you have to consider is whether to protect your equipment vs. cleaning up the power line noise without impeding current draw. The latter starts to get very expensive as the power handling increases. If a couple of grand sounds too expensive, there are surge protectors out there new and used for a few hundred dollars that will be far better than the $29.95 models at Home Depot.
4. Forget about "20 amp" power cords as these plugs are of different configuration. They only work (fit) if your gear has 20-amp receptacles attached to them. Your equipment will have the 15-amp adapters in the back so you'll have the standard 15-A power cord. Most standard big name power cords will easily handle 20-amps. Don't build a system around a power cord.
20-amp wiring is not overkill. Once upon a time, houses were wired with only a couple 15-amp circuits. All you had back then were a few light bulbs and a TV set. Today, new houses use as a standard 20-amp circuits for receptacles. What with computers, microwaves, window air conditioners, exercise equipment, kitchen appliances, power tools, workshops etc., it is practically a necessity. Plus, what it amounts to is a difference of 50 cents - the cost between a 15-amp breaker and a 20-amp breaker. Most receptacles today handle 20-amps and the same size no. 12 wire is used for both circuit ratings. If you want the no. 10 thicker wire, now you may be talking overkill if you're running less than 50 feet from the panel.
