Hey -- take heart - the NEC is a wonderful drive
Upgrade to Herrie's Firmware 1.07v2b4 -- it works just great
You can get more info here: http://club.cdfreaks.com/showthread.php?t=95819
Try to upgrade while in DOS mode ( true DOS mode ) ... download TDBs DOS flasher.
You can find it at: ( Get the NEC ND-2500A -- NEC2X00A.ZIP file )
Also read the post on top about Flashing firmwares - its easy (has its risks though).
BTW, I have no idea about this crackling sound - maybe someone else will chime in.
NEC is the absolute best in terms of DVD write quality