Removing the ground on PC?

Cheating out the ground may get rid of the hum but the problem isn't that you have a grounded chassis. The way to address the problem is to find the cause and address the cause. As Carl109 pointed out that the 'fix' of cheating out the ground has its drawbacks.

Carl109: I agree wholeheartedly. What further amazes me is that audiofiles will go to great lengths and expense to add 'tweaks' to their systems (most of which are meaningless) propose theories that audio equipment and music are too complex for even the most modern scientific instruments to measure, attempt to discuss subatomic particles and the philosophical aspects of current flow, but when there is a ground loop hum, what happens - "let's chop off the ground - look ma no more hum, ain't it grand".

That depends on whether your interconnect is connecting the chassis of the source to the chassis of the preamp. If the interconnect is connecting the chasses then no, you still have all chasses grounded. However, if that is true, that then I would consider leaving your ground intact on the power cord from the source to the power conditioner and lifting the connection of the shield pin on one end of your interconnect. That is likely the connection that is causing the ground loop problem.

I tried to post this yesterday but it didn't make it to the forum, so if it gets posted twice, that is why. I must concur with Carl109 as to the quality and efficacy of a safety ground connection made by the shield of an IC. I completely agree with him that this type of connection is likely not capable of carrying the fault current necessary for protection. Additionally, you run the risk of too high of an impedence to ground to reach the current needed to trip the breaker due to a hot chassis. Since the chassis of the equipment sitting next to the source does have a low impedence path to ground, touching both boxes at the same time could prove unhealthy. These problems don't occur when you ensure electrical safety via the designed method. I strongly recommend against defeating the intended safety ground and do not endorse relying on a ground provided by an IC to protect against fault currents. Besides, there is no good reason to do this. Solving the problem correctly is possible without creating any hazard.