Bret Halford
500+ Head-Fier
1.3 have some pretty epic bass boost stretching into the mids, which makes them seem a sound bit less bassy and more warm.
5.3 much closer to slam of 770 (80)s, has a bit more upfront around 100 Hz and maybe a bit higher extended to sub and flatter treble.
1990 with balanced is a brighter can than the rest, analytical pads more so. If you can imagine 1990 or T2 with a high shelf rolling things off >1kHz. It's pretty smooth, but some find the 1kHz null too much... that's the 1.3
I am firmly of the opinion that Beyer tried to bake in some of the tube amp synergy people loved on gen 2 and prior versions, I wouldn't want to add more warmth with tube or hybrid... I'd probably go Jot, but high power amps are at best not going to cause problems on this (and could definitely add problems, depending on your sensitivity to oversat and related issues).
5.3 much closer to slam of 770 (80)s, has a bit more upfront around 100 Hz and maybe a bit higher extended to sub and flatter treble.
1990 with balanced is a brighter can than the rest, analytical pads more so. If you can imagine 1990 or T2 with a high shelf rolling things off >1kHz. It's pretty smooth, but some find the 1kHz null too much... that's the 1.3
I am firmly of the opinion that Beyer tried to bake in some of the tube amp synergy people loved on gen 2 and prior versions, I wouldn't want to add more warmth with tube or hybrid... I'd probably go Jot, but high power amps are at best not going to cause problems on this (and could definitely add problems, depending on your sensitivity to oversat and related issues).