RemedyLane
Congratulations on your purchase also. They are a great set of cans, and combined with my MG Head, I was up very late last night!!
Ok,let me toss my hat into the ring on this cable up-grade thread.
First off, my bio. I'm more than likely old enough to be some of your guy's dad,( 49, but who's counting ). I have been involved in high-end audio for some 25 plus years. I have owned and sold alot of high-end equipment over the years, managed a high-end audio store for 6 years, and I was a factory trained repairman for JBL and Altec Lansing speakers. And I play guitar, ( long live the Fender Strat! ). I love tubes and tube gear.
As you know, this IS all about opinions, and heres mine. Good high-end audio cables and interconnects can add both good and bad, but the botton line is they really should be completely NEUTRAL and pass along the signal without altering ANY characteristics, IMHO. If you want frequency changes, buy something with tone controls. I have measured and listened to many cables that alter the frequencies in various areas, creating perceived improvements to the sound. And when cables start to surpass the cost of the equipment they are connected to, one must really perform a reality check to see if it's worth the cost, and even more so, are you just imagining the improvement. I know from my own experiance that when you can run subjective A/B testing, most people cannot repeatedly pick-out some VERY expensive cables from lesser ones, unless those cables are ALTERING the sound.
There, I think I fell off my soap box!!!!
Anyhow, enjoy your new 600's RemedyLane. I know I will- JUST THE WAY THEY ARE!