As we all know/heard about, that moving coil loudspeakers are reactive loads. Reactive simply the current will lead of lag the voltage phasor (or the incorrect but popular term "vector"). If current leads voltage, it would be considered capacitive because a capacitive load will draw current that leads the voltage, a pure capacitor will draw current that leads voltage by 90 degree. Cosine -90 or +90 degrees = 0 so at such high phase angles, the amplifier will virtually dissipate heat (watts) in the amp's output devices and not in the speakers.

So whether the load is capacitive or inductive, if the phase angle is too high, it is not going to be amplifier friendly. I don't know how your Canton speaker's phase angle looks like so I can't comment on whether the AVR-X3700H can handle them. It is best to email Canton and ask them about it. When you do that, you may want to give them a link to Amir's test results.

In general, I would think that a combination of low impedance and high phase angle would be tough for any AVRs and many power amps. But if you don't see anything like 4 ohm+phase angles >45 degrees combinations, I wouldn't worry about it as I know Denon/Marantz amps are quite capable of "high current".

If the phase angle of the load current is leading, the load is capacitive, and for the same phase angle in magnitude, it is a little worse than an inductive load because there would be a higher risk of the amp getting out of its comfort stability zone. To explain that I would have to brush up on my control theory, remember the poles and zeros, bode diagrams, root locus analysis kind of stuff?...

I started cleaning up my basement but I have not thrown away all my university text books yet, but........