Hi, I had a quick question about the warranty. I bought a pair and sent them in and got back a pair of white/black B5's. Now the pair is worn down and I am looking for another pair, but I was wondering if I buy a different color B5 can I send in my old pair with the new receipt so I dont have to worry about wearing them down in 6 months? Or would I have to buy the same color? the size would be the same... Thanks!