Let me just say I'm dismissing "I heard it" only as a evidentiary proof that one interconnect is better than another. I am a firm believer in going with what sounds best, regardless of the price. I often find $1000 speaker sets sounding better to me than some costing 10 times as much. But in that case, and in the case of most parts of your audio system .. there really is a difference in sound - and it by all means is up to the consumer to pick what he or she likes best, regardless of the brand or cost.

The main difference in the case of interconnects is the reluctance of those claiming major sound improvements to participate in double blind trials. There have been several tests conducted where so called "golden eared" audiophiles auditioned what they thought were many different interconnect brands. As they got more expensive (and in some cases, just thicker) of course they heard vast improvement .. when in reality the interconnects never changed once the whole time. There are proven psychological reasons for this phenomenon.

As for burn-in .. I agree with burn-in when it comes to speakers .. new speakers will be a bit "stiff" before they settle into the state they will occupy for most of their existence. But burn in for a cable?

Here is an excerpt from one of many who has taken on the burn-in myth: (long)

"We keep hearing that cables (some will say all audio equipment) should be subjected to various techniques to "stabilise" them. This is generally referred to as burn-in, and after the treatment the item(s) supposedly sound better. To aid this process - of course - many entrepreneurs have slaved away for whole minutes to create CDs with pink noise or some other signal "specially designed" to do the job properly.

So far, I have not seen a shred of evidence that any so-called treatment has any effect whatsoever, other than a psycho-acoustical phenomenon known as "getting used to the sound". This indicates that it is the owner's ears that get burned in, and has nothing to do with the cables.

OK, so I am claiming that there is no change in the cable. I have measured cables (as have many others before me), and normally expect to find three main characteristics and two that are not relevant to audio. These are (respectively) ....

Resistance - influenced by the length and diameter of the conductors, and to a very much smaller degree by the purity of the copper used
Capacitance - influenced by the distance between the conductors and the insulation material. The capacitance is also proportional to the length of the cable.
Inductance - influenced by the cable length, diameter, spacing, and the amount of twist between the conductors
Self resonance - in any cable suitable for audio this is insignificant, as it is (or should be) so far out from the audio spectrum that it will have no effect whatsoever
Impedance - all cable has a characteristic impedance, and like self resonance it is meaningless for audio unless interconnects or speaker leads are many kilometres in length - this is unusual.
To some degree, the above comments are tempered a little when radio frequency interference (RFI) is present, but it will ultimately be the way the cable is terminated that makes a difference (rather than the cable itself).
It must be understood from the outset that cables are not very smart. In fact, they are bereft of any knowledge of anything. Indeed, their own existence is unknown to them, and their memory is much shorter even than that of a goldfish. This rather generalised statement applies to the conducting and non-conducting (insulating) materials alike.

A cable has no interest in the current flowing in it (or not) unless it is greater than the current carrying capacity of the conductors, in which case it will get hot (or perhaps only warm). This increases the resistance, but only for as long as the overload lasts, and until the cable returns to ambient temperature. This will take a few minutes at the most.

As long as the temperature is kept well below the melting point of the insulation (or the copper), no permanent change occurs. This is an extreme example, since in practice most cables are at room temperature, and may gain but a fraction of a degree even at maximum amplifier power. Any current that may have flowed at some time is instantly forgotten.

Likewise, the insulation is not the least interested in the voltage that may have existed between the conductors once it has gone away - again making a valid assumption that the output voltage from the amplifier will not cause the insulation to break down, allowing the signal to arc between the conductors. There are some very minor effects with all insulators (dielectrics), where a short memory effect can be noted, but this is not at all significant for audio, and even less so in the long term.

The end result of this is that cable burn-in is an invalid concept. More than just invalid, it is an attempt to convince you (the buyer) that the reason the expensive cable(s) you just bought don't make any appreciable difference, is that they haven't been given the necessary treatment, so you should buy this CD (or some other overpriced piece of equipment) to rectify the situation.

The simple fact of the matter is that changes in room temperature will cause a far greater variation in the characteristics of a cable than pink noise applied for a minimum of 37.5 hours. At the end of the "treatment" the cable will still exhibit exactly the same resistance, capacitance and inductance as before - so what has changed? And the answer is .... nothing.

There are electrical principles that exist despite any marketing hype. The hype and bullshit does not affect these principles in the least, and there is absolutely nothing you can do to a cable with a normal signal that it will remember or that change its long term characteristics."

- pink.