Question on grounding for disc spinners

[bhanja_trinanjan]

Hi,
Why is it that a majority of Blu-Ray players and DVD players have 2 pin AC power plugs, without Earth (Ground) terminals?
Most premium CD players on the other hand have proper 3 pin power plugs with ground terminals.
I have noticed that using a non-grounded disc spinner with an amplifier sometimes introduces a hum in the audio signal.
Is it advisable to connect a Blu-ray player with a 2 pin AC cord to an amplifier? Will it degrade sound quality by introducing electrical noise?

 

[jls001]

Most CD players are designed for two-pin power supply. I have seen the top of the line Marantz SA-11s2 at very close quarters, and it uses two pin supply. So does their entry level CD-6003. Some players do use three-pin power plugs but provide ground lift (i.e., it's possible to make it ungrounded).