Can't agree more with fsmithjack, that the source first approach is the right one and with bigkidz. If you leave your source and upgrade downstream, it will sound different and maybe even "better", but the limit will always be the signal fed into the chain of equipment. I guess: It's possible that you like your current system because you can listen to it for long periods without getting tired. If so, then it is probably because it sounds natural to your ear - good musicality (described in more detail by bigkidz). In my experience it is very easy to mess this up when you upgrade downstream (cables of equipment) only as better downstream equipment may sound more impressive and revealing etc, etc, but it cannot improve the fundamental quality of the sound - the musicality - coming from the source. Only a better source can do this. As a matter of fact I found that even though a downstream upgrade sounds all that better at first, it leads to listeners' fatigue quite quickly. The example mentioned by larryi has been experienced over and over many times and has been reported on by many audiophiles around the world - this may be a hint in itself of where to look for the best upgrade path. Once a source of the right "level" (as can only be judged by yourself wrt money, musicality etc) is in place, the enjoyment will improve significantly. This should last for a long time. Then a cautious selection of the right downstream upgrades (as per almarg post) will yield improvement without degrading the musicality of the system. All this of course IMHO.
