There a several magic numbers and divine ratios to be found in the natural sciences. I won't pretend that this is one of them, but it has been my observation (over 30 years of buying audio stuff) that, much like a doubling of power to achieve 3db of additional gain, a doubling of cost is needed to realize a significant difference in quality of components at ANY point in one's system. I know that some products are better values than others, and there is a lot of outrageously overpriced crap available. However, as a general rule, you will need to spend your $1000 to replace something that sold for $500 or less in comparable condition (new, used, auctioned, etc.). In other words, replacing a $1000 amp with a $1500 amp will yield imperceptible improvement, unless the former was flawed or the latter bought used. Replacing a $500 CD player with a $1000 CD player will almost certainly be significant to any listener. Make your investments accordingly. Buy used whenever possible, especially low-level electronics, and wire.