took a look at this awhile ago, but Gobel doesn't appear SET friendly (h/t JA):
Göbel specifies the Divin Marquis's sensitivity as 92dB/W/m; my estimate was a little lower, at a still-high 89.5dB(B)/2.83V/m. The Divin Marquis's impedance is specified as 4 ohms with a minimum value of 3.4 ohms at 95Hz. The impedance magnitude (fig.1, solid trace) remains between 4 and 6 ohms for almost the entire audioband, with a minimum value of 2.9 ohms between 83Hz and 99Hz. The electrical phase angle (dashed trace) is generally low, but there is also a current-hungry combination of 5 ohms and a phase angle of –45° at 26Hz. I used the formula in a 1994 JAES paper by Eric Benjamin to calculate what UK writer Keith Howard has called the "equivalent peak dissipation resistance" (EPDR, footnote 1). The Divin Marquis has minimum EPDRs of 1.77 ohms at 25Hz and 1.53 ohms between 53Hz and 57Hz. Though the EPDR is close to 4 ohms in the midrange and treble, this Göbel loudspeaker will work best with amplifiers that are comfortable driving loads below 4 ohms.
You basically have AG Trios as a modern, SOTA alternative.