Do It Yourself

Hi all. I'm splitting 2 XLR line level audio signals into 3 channels each. I bought one nice device (used) online called the Whirlwind SPL1x3LL (line level). Unfortunately I can't find another used one for a decent price. However there are plenty of mic impedance matched units, SPL1x3MIC which according to the manufacturer are identical except the impedance difference. I'm good at soldering and the devices are fully analog (no PCB), so I'm considering doing the conversion myself.

I was curious what it would likely take to convert the mic box to a line level box? Is it just a matter of adding a resistor somewhere? Seems like an easy way to save $100 without buying a brand new unit. I looked into my line level box and the is one component I don't recognize where the out signals split away from. My only hesitation is that I buy the device and end up needing a specific part or it turns into a larger job than anticipated. Just figured I'd entertain the idea before buying brand new. Thanks.