Dear Curtis –
You are attempting to use the XLR inputs on your mixer because you want to plug in the XLR cables from your Decklink Extreme cables right into your mixer. Almost 100% of the mixers manufacturered today use the Tip Ring Sleve stereo phone plug inputs (clearly labeled LINE INPUT) for the +4dBu line level input, NOT THE XLR MIC INPUT. Blackmagic, AJA, AVID, and every other manufacturer in the world keep with the +4dBu standard of audio to match professional equipment like Sony and Panasonic VTR’s – and you can plug your XLR cables directly into a Sony VTR and get the correct levels. AND GUESS WHAT – so do all the audio mixer companies – except they universally use the 1/4″ TRS phone plug as the +4dBu line input. This is done by Mackie, Behringer, Soundcraft, Yamaha, Tascam, Phonic, and everyone else you can think of. The XLR inputs are for microphones, and have some “trim” capability, but are not designed for line level inputs.
Do you know why this is ? Because the Mackie Mixer (the original cheap mixer) – was designed for bands that play in bars, and they wanted to plug their mics into a cheap mixer, and any “line level” products a band would use would be like a keyboard, or guitar thru a processor, which all use 1/4″ stereo phone plugs. Once the Mackie 1604 was released a long time ago, professionals, that were used to spending $4000 for a Soundcraft 200B, or Sony MX-290 mixer (all used XLR line inputs) – said SCREW THIS – lets get a cheap Mackie, its just as good, and it’s 1/4 the price. And the sacrifice was having to get different cables.
After 10 years, NO ONE is willing to spend $4000 for an analog mixer, and EVERYONE started making CHEAP MIXERS just like the Mackie, that used 1/4″ stereo phone plugs.
So the answer to your problem – GET XLR to 1/4″ (stereo phone plug) cables – END OF STORY.
bob Zelin