Michael, you may actually own the Perikles Reference, with 2 12" woofers on the rear.
Personally, while I do like this amp a great deal, I would be skeptical of any 300B SET amplifier with these speakers. That said, Jeff normally produces phenomenal (IMO, best of show) sound at the myriad venues he displays, and I think he may have used a 300B(?) based Tron amplifier. Folks have assured me the Border Patrol amplifiers, with their novel choke input power supply could do the job, but when hearing them with smaller woofered loudspeakers, I remain skeptical.
In my experience of living with them, despite the Lowther midrange, these Hornings work best with a surprising amount of power. Nothing against the 300B, as it's certainly a beautiful sounding tube, but I find it too soft on the low-end to get the Hornings to sound right. In my opinion, you need an amp with a pretty stiff bottom end, otherwise, the Hornings come off all wrong. If you don't use an amp that takes control of those woofers, the bass goes MIA, and the overall sound is quite unbalanced.
Best amplifiers I've used with them: 15 wpc Deja Vu push-pull 2A3, a Chinese 30 wpc push-pull transformer coupled 6AS7G, and 60 wpc Jadis DA60. The DA60 might surprise, but the speakers really loved the power, while 30 wpc Jadis DA30 and 40 wpc Jadis Orchestra Reference were not good matches.