It was the advent of the K712s where the newer pads brought more body and bass to the table than all the previous K700 series....excluding the similar sounding Annies which the K7XX are modeled after... but with the newer 712 pads....so that K7XXs with their wider sound-stage sounded IMHO much closer to the 800Ss than Senns own 600/650s. : )............I've never heard of the K7XXs being called the poor man's HD800s but I'm poor and I have the K7XX so I'll take it.
Haven’t even had a chance to get the HD6XXs burnt in and these show up to lean with the big boys….previously had the K712s and going from memory the “Red’s” appear to be the exact same headphone, with a slightly better fit (less loose)…again going from memory… And as I noted in my K712 review awhile back “When AKG meets Sennheiser and vise versa” in contrast to their initial release back in 2003 the current AKG K7 and Sennheiser HD6 series appear to be getting closer than ever to sounding similar..... the AKG having a bit more base extension and bloom.
May be just my imagination but I'm finding these K7XX's a more balanced/ satisfying listen over my previous K712s, sort of the poor mans HD800S, much more so than the HD6XXs I also have on hand....direct comparisons between the 7xx and 800S obviously show the superiority of the Sennheiser technology but a few minutes on my head and all is forgotten. Nice headphone IMHO
Anyway...I regress....back to the wonderful sounding HD58Xs.