After lots of trial and error I tracked the source of the problem to the brightness level on the 191T. At a brightness level of 63 or less the noise is pretty loud. I even installed various sound cards in the system and each one picked up the squeal. The Card Deluxe from Digital Audio Labs, a very clean card, couldn't fend off this obnoxious pollution.

Just to be sure, I experimented with a combination of power supplies, video cards, hard disc controllers...I basically swapped out a variety of components that could potentially cause noise interference with a sound card. In the end, the only viable solution was to simply turn the LCD off or increase the brightness level.

I checked for other possible problems from the power source. I installed a line conditioner from Furman to see if that would help. Again nothing worked.

I know back lights are common culprits when it comes to generating noise but I was surprised at how obnoxious the noise pollution from this monitor could be. I managed to kill most of the noise by the super fancy high tech solution of cranking up the brightness control but a bit of lower frequency hum still lingers.

It's the familiar 60Hz of a ground loop. Ebtech's hum eliminator should help with this. I did a quick test by lifting the ground on the connector to the Samsung power supply and sure enough that killed the last bit of hum. Wouldn't you know it, one of my most expensive pieces of gear I prefer to keep plugged in properly is causing the most noise.