recabling my Stax sr-009 to pure copper cable

Generally speaking, my experience has been that silver, being the second best conductor we can use besides gold, is one where silver will improve performance across the board on all levels. Initial 'tinniness' will always occur in cables with silver because I suppose it's some kind of chemical trait. This trait will give way later on after the cable has fully broken in, but this takes time. TRANSITIONING TO COPPER IS NOT RECOMMENDED because copper is completely inferior as a conductor. The 009s are known for a particularly sharp sounding signature, so I'd personally recommend either waiting longer until after the headset has broken in some by playing music on it for long periods as others have suggested or completely eliminating the problem by getting a tube energizer to fuel the cans. The latter is money restrictive, but would definitely provide a definitive solution. Whatever you choose, I would strongly recommend sticking to the silver cables, as Stax is one of the few companies that understands the value of good cabling on their products. There's a reason they don't allow interchangeable cables on their sets. 

Try a different driver amp!

Do not screw with the cable!

I have now heard the 009s on my amp (Blue Hawaii SE), and it is somewhat on the bright side and not quite as good in the midrange as the 007.  I can see why someone might be tempted to change the wiring, although I have no idea if that will work out well.  I am still considering an 009 because it has better bass response and dynamics, and does not require the amp to work as hard (more efficient).

For speaker wiring, I have found that silver wires sound more extended on top, but, when done correctly, silver wiring is particularly nice (don't know about silver-plating).

By the way, silver is MORE conductive than gold.  What gold has going for it as a conductor is that it doesn't easily oxidize.

By the way, silver is MORE conductive than gold. What gold has going for it as a conductor is that it doesn’t easily oxidize.

+1. Both silver AND copper are more conductive than gold, and by a considerable margin. See the resistivity and conductivity tables that are widely available for various metals, such as the one in this Wikipedia writeup.

That being said, in the case of a home audio system it can be shown analytically that under most circumstances whatever sonic differences may exist between cables made of these metals are not due to differences in the resistance and conductance of the metals, assuming the cables being compared are of equal gauge and length. A possible exception to that being speaker cables, in situations where cable length is long, speaker impedance is low, and wire gauge is narrow.

Also, to add some perspective, simply making a copper conductor one gauge size larger will lower its resistance by well over twice as many percent as it would be lowered by changing the original copper conductor to a silver conductor of the same gauge.

Regards,
-- Al

Since the Stax 009 cables are not interchangeable, I would refrain from changing them. To me, that's like changing the engine in a Ferrari to a high performance Chevy engine. It might go faster, might not, but what's the point? If you want a different sound, buy a different headphone (one with interchangeable cables) then experiment with different conductors all you want. The idea of cutting through the flat Stax cables and then twisting or soldering the wires to other types of cables is ridiculous. Ruin them if you want to, they're your headphones, but at least you have my opinion.