I'm a bit shocked at this answer. Why in the world would anyone want to use a high impedance mic, or even use a low to high impedance cable converter in a pro situation? No where in the pro world is something like this found. I would also guess it would be met with similar confusion as I have in reading this "solution" to a high input gain situation.
Even with a high output mic like a Beta 52, there are many more mics oout there with even higher output levels as models from AKG, EV, Sennheiser, Audix, etc. all have. I prefer to have the clip light on most boards I've worked with to light up when the kick is hit for an instant so I know I've got the hottest signal to noise I can work with (most recording or PA consoles have anywhere from 2db up to 10db of headroom above the clip light indicator before the signal actually begins to clip) and then EQ as needed from there as long as the drummer has a clue on how to tune his own drums (Most do not and is the only instrument that someone can get paid to play and not know how to properly tune - think about it.).
And there is no PAD switch on this mixer? Plus your response of using a 1/4" input as the solution to the previous statement about the very understandable concern regarding a feature not working worries me big time. How does anyone work with this mixer if you can't adjust the input gain level for any XLR input signal for the sale price of $2,500.00?
I hope Line 6 is coming out with a fix to this feature malfunction as well as perhaps an internal software version of a PAD switch for those of you who already made the purchase of this unit. I'm glad I chose not to "leap" before looking here for the remarks of those who have purchased this unit.
While I'm here - anyone reading these posts go to any of the in-store demonstration of the full PA system? If they are miking up a band for demo purposes, I wonder how those demo people are getting around this very basic input signal situation as mentioned?
One of several ways I know to get around a situation like this is to use an AKG 414 at about $1,000.00 per mic unmatched (They come in response Q matched pairs for use in many applications where you want the exact same response from two of these mics if anyone did not know why I mentioned that.). That model mic has it's own -10 db and -20 db PAD built right on the mic. other high end mics available also have the same built in PAD features. That's one way around this input problem, but at a very high cost.
Another way would be to use an XLR attenuator adapter or cable adapter. Much cheaper and does work, but it's not what I would expect to have to do for a mixer that costs as much as this mixer does.
Perhaps my suggestions will help those with this problem until Line 6 can come up with a much better resolution.
It is very common that especially a kick drum, using a microphone like a beta 52 or similar, produces very high levels. Using the 1/4" input on the combi inputs solves this problem.