“Why are my Mackie HR824 monitors extremely noisy and loud when I hook them directly to my Aardvark Direct Pro 2496 or LX6 card? Can I use them in this configuration?”
Yes, it will work just fine but it will take a little adjusting. The Aardvark Direct Pro 2496 and LX6 outputs are very ‘hot’ compared to most other audio cards. Because of this, the low noise floor they have is also equally loud. The good news is that Mackie’s HR824 has an “Input Sensitivity” control on the back of the monitor that comes in handy for situations just like this. Mackie ships the monitor speakers with the input sensitivity adjustment in ‘normal’ position, which has them running fairly hot. To compensate for the Aardvark’s high output, you can simply turn this screw adjustment down. In general we recommend turning the Mackie (or any amplifier’s) sensitivity control down so long as you can still get adequate level out of it. This will require you to drive the output of the device in front of it harder, which is desired (up to a point).