I received the Pioneer 110D OEM from NewEgg and swapped it out with my NEC ND-3550A and the noise difference is like night and day.
The Pioneer makes no noise during reading of DVD-R, DVD-RW, and DVD+RW containing regular DVD-ROM data or ISO-format data (eg, .avi, .mpg, .ts, etc). After several days of usage in my external USB device, the Pioneer's disc read noise level has never risen above 0 decibels.
I thought the first thing I had to do when I received the Pioneer was cross-flash its firmware from 110D to A10XL in order to use the Pioneer QuietDrive Utility, but that's not necessary. It's quiet out-the-box!
I'd like to thank chef again for his advice to go for the Pioneer instead of potentially wasting money on a DVD-ROM which may have been just as loud as the NEC. You were right on the money! You know your stuff!