I suspect that ((((as a general rule)))) this would be an excellent way to test the differences in cables, or really any other component for that matter.
High end headphones should provide a more detailed and direct presentation of music than you could expect from any speakers. The biggest problem you will have is that it will be very difficult in your headphone-based system to pick up subtle differences between various cables in terms of the soundstage aspects. (The one exception to this would be the AKG K1000 earspeakers which are essentially speakers hanging from your ears that do provide a very realistic soundstage).
As for the usual "trasparency" oriented issues that you might be interested in, no doubt your Senns are the place to start. At a minimum your "headphone test" will quickly tell you which cables are likely to be on the revealing/bright/detailed versus muddy/dark/veiled side in your speaker-based system. Sennheiser 580s and 600s tend to be laid back / veiled in their presentation but the right cable can really bring them to life as you've discovered.
Not to muddy the issue you've raised, but either the Equinox or the Cardas replacement cable is a must if you want to get the most out of your 580s (but it will more than double your investment cost - i.e., more expensive then the cans themselves). As with all things headphone, the best place to look for expert opinions is http://www.head-fi.org
High end headphones should provide a more detailed and direct presentation of music than you could expect from any speakers. The biggest problem you will have is that it will be very difficult in your headphone-based system to pick up subtle differences between various cables in terms of the soundstage aspects. (The one exception to this would be the AKG K1000 earspeakers which are essentially speakers hanging from your ears that do provide a very realistic soundstage).
As for the usual "trasparency" oriented issues that you might be interested in, no doubt your Senns are the place to start. At a minimum your "headphone test" will quickly tell you which cables are likely to be on the revealing/bright/detailed versus muddy/dark/veiled side in your speaker-based system. Sennheiser 580s and 600s tend to be laid back / veiled in their presentation but the right cable can really bring them to life as you've discovered.
Not to muddy the issue you've raised, but either the Equinox or the Cardas replacement cable is a must if you want to get the most out of your 580s (but it will more than double your investment cost - i.e., more expensive then the cans themselves). As with all things headphone, the best place to look for expert opinions is http://www.head-fi.org