How to know if GAN-fet amp and Lyngdorf 2170 (as a Pre and Dac) are compatible

I have no experience matching separates but have been advised to confirm compatibility between amp and pre to avoid performance issues.  The person warning me did not elaborate on what problems there could be, but suggested I will be good if the pre-out voltage is 2 or higher.  He mentioned 2.8 as an example.  Some pre-outs are as low as 1v, he said, which is not good.  I have a text into the US rep for Lyngdorf about the pre-out voltage, but suspect there could be more to ensuring good compatibility.

What if the voltage is 2?  Would it be good but not as great as if it were 2.8?   Or is it fine as long as it’s over a certain minimum value?

Another person suggested I “make sure the gain on the amp and the pre-out match”.  It seems a poor match can lead to the inability to adjust volume in adequately small increments.

I am accustomed to very precise volume control as the Lyngforf adjusts in 1/10th db increments.  I don’t necessarily have to have it that fine, but wouldn’t want to lose the ability to set volume where I choose.

If those in the know would be willing to bring me up to speed, I sure would be grateful,

Thank you,