Most overlooked part of your system?

I was intrigued by the title of the post, but disappointed to read that it was about cabling. I believe cabling can make a difference, but as has been said already, not as much as the components themselves. If the title were posed as a question I would have definitely said the room. That also can make a HUGE difference, and I'd look to investing time, effort and $ there before exotic cables. The potential for the room impact is far greater than cables IMO and in my experience. As far as the cables themselves, IC's before PC's. Source (to pre) first. That'd be my approach anyway. Clean, isolated power will have more bang for buck than just sticking in an exotic PC. If you pay an electrician to run a couple of isolated lines for your system, depending on your house, it may run you less than many fancy PC's, and, again, bigger bang-4-$.

A moderate investment in scotch, bourbon, tequila, wine or herb will reap
benefits well beyond the same dollars spent on wire, isolation or other
audiophile tweaks.

I doubt pouring any of the aforementioned on your stereo will make it sound better, but its worth a try.

Tvad - great response, I find a margarita really opens up my system, much more transparent,

on a serious note - I think all audiophiles should read Oliver Sach's recent book "Musicophilia". It is a great study in how much our experience of music is influenced by neurology and brain structure. All of you with "golden ears" should note a study by Psychologists. A number of subjects were played music that was familiar to them. Sections of the music were completely eliminated (silence) on the playback. None of the subjects even noticed the silences - the brain filled in the rest. We have an amazing capacity to accomodate musical sources and make up what we perceive to be missing. This would also create the possibility of a powerful ability for our minds to hear what we want to hear.

I am a firm believer that the "break in" period for electronics is much more about our ears and brains re-compensating than any electrical phenomenon.

Either way, the book is fascinating and interesting.

on a serious note - I think all audiophiles should read Oliver Sach's recent book "Musicophilia".

I started reading that at my sister in-law's place over the holidays. I made a note to pick up a copy. Another good read on the same / similar subject is This is Your Brain on Music: The Science of a Human Obsession. There is a recommendation blurb, as I recall, from Oliver Sachs on the back.