All of the above posts contain valuable info, but as to which approach is beneficial really boils down to YOUR environment and how YOUR system works within it.
Without knowing your environment/setup it is really difficult to assess which is "The Best" option.
One thing for certain - a dedicated power line and good outlets will reap benefits. e.g.
Getting other household appliances/lamps off the line can provide a significant reduction in interference and using a quality outlet provides better clamping of the plugs and hence a better electrical connection.
A good power-conditioner will also eliminate power line noise, but depending on the conditioner and your equipment you may experience some compression if you plug the amps into it - BTW this has supposedly been verified by the guys at Nordost, but then some might consider their opinions "extreme" :-)
Digital equipment (DAC, CD Player etc..) have been known to polute other sources and power-conditioners have been effective in addressing this.
External RF interference from our surroundings can also contribute to system noise. This however can be remedied either by ensuring a good grounding/shielding approach is taken in power cables, components and interconnects.
My personal journey started with a power conditioner, mainly because that was the recommendation at that time.
Once I installed the dedicated line I discovered my environment was not noisy at all, so I removed the power conditioner - today I even use interconnects without any shield - but that is in MY environment.
This may or may not be applicable in your case and as Zd542 says "There's no way to tell until you try it".
If it is relatively cheap to install a dedicated line in your environment then I would start there - even if you still require a power conditioner the benefits of a dedicated line will not be wasted.
Outlets I like - because they work and are reasonably priced are Pass & Seymour MRI grade @ $25/outlet - Take Fiver Audio sells cryo treated if you think that helps.
Cables I like - Furutech and DH Labs Power Plus
Power Connectors I like - Vanguard from Ebay - they are gold on copper and perform extremely well considering their $21 for an IEC and PLUG pair
There are some very good assembled after market power cables out there - some mentioned in this thread as well as many other threads throughout Agon - so do your research
If possible beg or borrow from friends or cosy up to a good hi-fi store and try as many products as you can.
Also - some of the noise you may hear could come from your components - caps do not last forever and can get noisy so consider this in your "quest for silence".
There is no quick answer - It took me two years to determine the root cause of my problems and how to fix them.
Here's a link that adresses some of the power supply issues and talks to available solutions
You Need A Goods Power Supply