Andrewdoan, yes, a power cord does take time to burn in, however 700 hours seems a bit excessive. From my experiences, you usually get a good idea of how a p/c will sound right out of the box. Generally, the cord's sound will change a bit over time, as it 'settles', but I've never heard a night and day difference as some folks have said. Usually, if a cord I've heard is 'in the ballpark', it can sound better over time. However, I've never heard a cord sound forward, have sharp glare, and too detail turn into a warm, sweet cord with time.
Sometimes burn in can take the edge off, but if the initial reaction is that negative, I don't think that's the p/c for you. There are many other good cords out there. It depends on what kind of sound you are looking for. There is a thread on the AudiogoN forums called 'Power Cord Flavors'. Maybe you could get some background reading stuff like this. Sure, it is not the Bible, and opinions will vary a bit on what aspects they look for in a p/c, but it will give you some ground work, a place to start.
Happy listening,
John
