but to my experiences , may not reflect yours but, the way i perceived sound never really did reflect on the frequency range, only if i played a sweep then id know, but when playing just normal music, the voice of the song always so much more preminent, on my MS mezzo, also british,
i dont know where to get the frequency graph, but it be interesting to see one, as my MS sounds very mellow, but when playing a sweep(www.burninwave.com ) it sounded somewhat neutral, (again this maybe due to my ears.)
i also think the way sound if produced is hugely influeced on the DAC of the pre amp/receiver or Sound card
because my asus xonar DX-well all xonars, sound warm, but they dont really have much impact on the freqeuncy range,you could well say the difference is pretty much unnoticable, if u are comparing from a high-end to really 'super high'-end.
however, when we listen to music, or anything other then a sweep/(any tests) we can tell lot of differences in how some part of the frequncy is somewhat more present. dont you agree?