Tweedly is right, there is an option on the 630 (and I assume the 430 as well) that allows you to set the front panel to fade out after a few seconds. All that's left is the blue light coming from around the volume control and power switch. It's that cool blue color that they use in airport taxiway markings. I've always wanted to put them down the sides of my driveway...

M- M60s/VP150/QS8s/SVS PC-Ultra/HK630 Sit down. Shut up. Listen.