Ah, he didn't capitalize "dual source" so I didn't know he was referring to Baggs. T-power. Oh, my. I haven't run that since the '80s. Phantom power standards were still settling down at that point. Our Neve consoles had no phantom so we worked with external supplies. Different mics, different power supplies. Sennheiser began appending the power system used to the name of the mic, ie. "MKH416-P48." That was helpful. OF course their MKH816 shot gun was simply MKH816 and you had to know that it used T-power. Back in the mic locker we've got forty-seven year-old T-power supplies, many with belt clips.
Recently, during a clean-out, an AKG N46E P48 supply fro the early '70s was deemed surplus. It and I had a long history together starting around 1981, so it was given to me.
Wow, I'm dating myself.
Bob