With respect to Panamax, they have quite a line of models, ranging from simple surge suppression to several with real power conditioning. I assume that when you say “power source” I assume you are referring to power conditioning, and not simple surge suppression.
The effectiveness of power conditioners depend, in part, on the cleanliness of the incoming power. A dedicated 120VAC line for A/V can certainly help noise problems, but may not be sufficient by itself. The higher-grade conditioners can certainly make a big improvement when you have poor quality incoming power, and the isolation transformer models are especially effective. In addition, the better power conditioners have the ability to isolate noise transmitted from one A/V component to another.
You may want to work with your dealer and do a home trial with the best conditioner you would buy, keeping within budget, to see what improvement you can discern on both audio and video with/without it in the circuit. If you cannot discern any real improvement, then consider a less expensive model, or just a surge suppressor. This is how I would approach the problem. I try to avoid throwing money at something that creates no discernable improvement.
The incoming noise level will probably vary, so you will have to do the test over several days and times of day. A blind test with someone else inserting and removing the conditioner from the circuit would be best to avoid biasing the results. If you do not have the time or patience for any of this, then buy the best power conditioner, you can (within your budget).