to save a bit of power (and annoyance), i de-soldered the leds on two usb soundcards. i use these soundcards for battery driven projects (beaglebone black) and every milliamp i can save counts.
the logilink soundcard had two easily removable leds. the red one indicated that the soundcard was connected and had power, and the green one started to blink when the card was in use (driver activated). both functions i can easily live without.
the blue '3d-sound' card had a very tiny surfacemount led that i removed using two soldering irons.
here some before and after photos...
btw, i'd stay away from the logilink. it has a problem with audible noise coming from the pwm signal of the green blinking led. if you connect a mic like i'm doing, a beep beep beep kind of sound leaks into the mic. and removing the led doesn't help. maybe there's something in the software driver to control it, but i doubt it.