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

Thank you guys for the suggestion. Appreciate it. I will remove power conditioner and listen to it on this week end. However, one thing I noticed when I introduced power center into this setup was that the improvement in sound stage.

Based on my testing in this weekend, three possibilities could happen. With direct connection, I could hear better sound or remains the same or worse. If it remains the same or worse, I will prefer to keep the power conditioner.

So, my question is will I see an improvement in using power cable with direct connection?. Looks like I may not hear any improvement in using power cable along with power conditioner - is it true statement?.

Almarg,
In my most recent testing, I followed the same steps as earlier i.e receiver connected directly to wall and rest all connected via power conditioner.

In few days I will connect everything to wall and repeat the testing and report back.

Wow, thanks guys for all the responses. Last night I had an opportunity to test the system with and with out power conditioner. I hooked Yamaha receiver directly to the wall outlet and let other components (CD player, ML Grotto subwoofer) connetced to power conditioner.

When I switched between power conditiner and direct wall, I did hear a clear difference in low and high frequencies. When connected to power conditiner, subwoofer sound is much tight, precious and clean. Also, high frequencies were very forwarding. I didn't hear any difference in mids.

Based on my limited testing, I could say power conditioner did improve sonic. I will do more listening over this weekend.

Also, I found out that the wiring that supply the power to my syetem is shared with only other outlet - that's being used for lighting. So, if I turn off the lighting (while using the system) or re-direct the lighting wire to some other source, could I say I have a dedicated line to audio system?. That outlet voltage consistently remains between 120-121 haven't seen gone below 120 yet.

As suggested here, I will do home-trial of few power cables and report the result here. If I were to do that, should I replace the one from wall to power conditioner or power conditioner to receiver or both?. I will also try direct from wall.

Please note that I go by my ears and not by any measuring equipment.

Like wise I said earlier, I did some detailed listening between direct wall power vs through power conditioner. Definitely I did clearly hear tighter, clear bass with power conditioner. On highs, it is more clear and detailed and could easily say that sound waves lingered around my ears more than one without power conditioner.

I am no means an expert in audio/electrical engineering but based on my testing that is what I found out. I am getting an Oyaide SWO-GX outlet from another audiogoner.

Next, I will get a good power code before trying for a dedicatied line (wife factor :) ). Atleast, my outlet is not shared with any other gadgets such as fridge/heater etc but for lighting the room.

I also used Isotek CDs few times and that helped a lot is soundstage and localization of soundfield. As of now when I play music, my speakers disappear - I could separate the instruments and localized them (based on the recording). Hoping power outlet and a cable improves it further.