I had a problem with an oscillator on voice 2 dying last year, I sent it to electron and they replaced the main processor.
I’ve had the a4 back for about 4 months now, and voice 1 sounds distorted, a good distorted, but not as bright as voice 2.
Is there a calibration that I am missing maybe?
If you don’t find an easy fix here, I would reach out to Elektron again sooner rather than later. I’ve had a friend experience the misfortune of a filter dying, the main processor board being replaced by Elektron, and a second filter card doing the same shortly after.
ugh
You can calibrate the unit with the FUNC + power on menu, I had a problem with the four voices and it was solved with a calibration
I guess depending on the cause this isn’t all that unlikely, if maybe a little unfortunate.
There’s a general philosophy when doing repair work on cars that if you’re replacing something that comes in a pair then you replace both of them at the same time. The idea being that if one died then the other probably isn’t far behind it, and it’s generally easier and cheaper to do both at the same time than turn it into two separate jobs.
But yea I’d try calibrating in this case 
This worked for me.
All voices are the same again, really cool and interesting that the Elektron service department never told me about this.
I’m glad it worked, they advised me to do it as a last resort, if it didn’t work I should have sent it in for assistance too