So the cable on my Portapros gave out after a few months, so I looked into Koss' lifetime warranty, and it states that I must send them a check for $9 along with the defective product. Can I just send them the $9 in cash? I don't really have a bank account, so I can't write a check.  

  I come to you with a budget management question.  Right now, my current setup is just a JVC HARX900 with a PA2V2 amp and my PC's onboard audio, listening to music encoded in FLAC.  To "upgrade" my listening experience, I was wondering whether I should buy a USB DAC, or get better...