power cables where do I start?

Might consider Audio Art power cables, have made noticeable "positive" SQ differences in both of my full rig systems 

+1 for Audio Art

Also consider Triode Wire Labs.

Power cords will make a difference. Best of luck.

+2 for Audio Art .

Why not have Klaus make up some cables for you?  Their synergy with his equipment and the Groneberg cables is great.  Your amp is wired with the Groneberg cables so the power cord would be a natural extension of it.  You can post a message on Odyssey Audio Circle stating you are looking for a  Groneberg power cord and I am sure you will have people willing to sell.  That's how I bought all my Groneberg cables.

Every change will alter the sound somewhat, whether is better, or worth it, is up to you.
That being said, I would consider Zu Audio power cables. They sell older models on Ebay for a fraction of the original cost, and they are well built and perform just as good as more expensive cables.
B