Some of 'em aren't quite as high as 20 ohms. The 8dB and 10dB versions, for example, present a slightly lower impedance than the 12dB and 14dB versions. And really, even the 14dB unit only presents about 15-17 ohms at its maximum, depending on the driver used. There's a smaller shunt value and higher series value in the 8dB and 10dB assemblies, so their load is even a little closer to the 8-10 ohm range. But I still like to point out that impedance is slightly higher than some might expect due to the compensation circuit.I can't recall which cable assemblies you're running, or if yours are different. But the load impedance is pretty easy to find, it's a simple circuit.