I haven't used the K-Max but I believe it's the same burrs as the K-Plus. I thought mine was kinda giving me more sour / acidic under extracted tasting coffees for a while before it was seasoned (both espresso and pour over / aeropress). I got a Niche Zero around the same time and thought they tasted very similar, also under extracted weak or acidic and unbalanced. People sometimes say conical bring out the 'fruit notes' in coffee, which I think is false, but at the time I thought 'Oh THIS MUST be what they were talking about'. I sold the Niche but I think it started getting better towards the time I sold it (did the next owner a favour seasoning the burrs!) and the K-plus also eventually changed, I remember comparing it to the flat burr grinder again later and being surprised at how good the k plus was, and not tasting sour /under extracted. SO I think using un-seasoned conical burr grinders MAY be why a lot of people seem to hate conicals. Flat burrs can benefit from seasoning as well but I think due tot he larger surface area the conical burrs benefit even more from seasoning.

I did get a barely used (not seasoned) Niche Zero recently again and it seemed good without needing seasoning so not sure if they're treating the burrs or changed something up or maybe I just didn't know how to brew coffee back then, but my flat burr grinder seemed more balanced with the same or similar brewing parameters back then so basically take this with a grain of salt I guess. BUT if you get weak or under extracted coffee, I'd say that's something that will improve as it gets more use! You can adjust brew parameters to try to combat / counteract that but keep in mind you might need to reverse that later on!