I don't really know how to answer this because to my ears the WM1ZM2 and the N30 LE are quite colored sources. I feel like there's a difference between having a tasteful coloration or warmth, not really having any, and then coming off as cold. For me the R8II sits between having a tad bit of warmth but overall still remaining very neutral in the FR. I don't think calling it either neutral or neutral warm would be inaccurate, but it doesn't have that typical warmth I'd associate with a bass boost or perhaps more relaxed treble.
I feel like what I'm saying makes zero sense as well...
but if you ever get to hear it maybe you'll understand what I'm saying.