Do I need a power cable - if so what brand?

Satiger (the original author of this thread, we almost forget you,eh?),
Krell and Nordost brand are great but they're no longer on my number 1 pick due to their unique characteristic. However, as a beginer who wants to see if there's any diff, I highly prefer to give Nordost a try. Any entry level models would probably be ok.
Try it on your source (CD,DVD) first.

I recently changed amplifiers and have been a bit dissapointed with the results of the upgrade. Rather than run out and buy a bunch of expensive cables, I am pursuing tweaks such as Room acoustics and power. I admit to being very skeptical about spending absurd amounts of money on wire and interconnects.

So today, I ran out, bought some Romex and added a dedicated circuit for my amp and DAC still using the stock power cable. I have to admit, it did make a difference. My amp is plugged in direct now, the transport, DAC and DVD player are on a power filter/surge protecter, the TV and cable box on a separate plug. I notice an improvement in transparency and separation between instruments, soundstage is clearer. Cost - $15 bucks as I already had an open breaker and the run was 15 feet plus a couple of hours of label running the wire and hooking it up. I may even try buying a decent receptacle!.

Thanks for the reasonable and thoughtful input - there are ways to improve sound without spending a ton of money and buying into the myths - next is DIY acoustic room treatments.

Almarg, as you probably realize, I'm not very knowledgeable about electronics. I do know that one cannot just use theory without the practical. For instance, before people could measure conductivity, they may have preferred silver over copper, and didn't know why. Later on, they found out that silver was a better conductor. There may be something going on that theory doesn't currently support. If it turns out to be true, than we have to look at why. This allows us to modify that original theory.