In electronics it is largely true that there is little new under the sun. Witness the resurgance of 80 year old directly heated triode amplifier designs, the simple is best school of electronics and the continuation of a love for the sound of tubed electronics.

Now having said that, I don't think it is nearly as true for digital electronics. The whole field is new enough that "discoveries" are still being made and incorporated into new designs. D to A chips continue to improve, oversampling and up conversion continues to expand its penetration into cheaper players. Digital "enhancements" keep getting more complex and the reviewers tell us that these techniques improve the sound that is acheivable in cost no object systems.

There is of course the question of balance, there's little point in putting a $20,000 CD player ahead of a $150 Pioneer receiver (an exageration but the point is valid). All systems have a performance limit or floor caused by many factors. If the limit in your system is near the output end, such as speakers or the power amplifier, improving the input has very little value.

My first "high end" CD player was a Denon 20 bit 8 times over sampled player. It sounded better than a mass market unit but not much. As I continued to improve the rest of my system the difference between the players became more marked. In other words the improvement of a CD player can only be heard if the rest of your system is up to the task of letting the imrovement pass through. As you might guess the Denon eventually became the limit in my system and it was replaced by a pair of seperates, a transport and an outboard D to A.

If you read my posts you will find me a strong advocate of outboard D to A's. The CD player is a mechanical device. It will wear out and relatively soon. Why pay for expensive digital to analog conversion every time the transport fails? I'm on my third transport but my current D to A will probably stay in my system for many, many years. I mainly buy transports that are mechanically sturdy. Unlike others, I do not hear a difference in one transport to another, but my D to A has quite a complex jitter correction circuit which might explain why.

So, yes buy older electronics made by well regarded brands, temper this with the knowledge that digital conversion circuitry continues to improve. Newer CD players will probably outperform older players assuming the price points were similar when the equipment was new. I find that the more expensive equipment almost allways sounds bettter (damn!)