I bought some new m90 rims for very cheap (considering). I’m be built them up with hope pro 4 hubs and Sapim race spokes. They are true to within 0.02” (with a dti) and spoke tensions is equal and dish is correct.
When I bang the wheels on the floor To mimic an impact they make a “bong” both wheels do it but the back more so. (Possible became its the back one).