Magico S1

Regarding amplifier sensitivity, I see that the S1 has a nominal impedance of 4 ohms, and presumably its impedance goes lower than that at some frequencies. Unless the variation of its impedance as a function of frequency is particularly small, the sonic presentation of a speaker having low impedance will vary considerably more depending on what amplifier is driving it than it would if the speaker had a higher impedance. Especially if one of the amps being tried is solid state (presumably having near zero output impedance), and the other is a tube model (which can be presumed to have significant output impedance)

That doesn't say anything either good or bad about the sonic quality, transparency, and musical resolution the speaker can provide when used with the right amplifier. It's just a consequence of impedance interactions, and perhaps also the current capability of the amplifier, and it just means that amplifier selection becomes more critical.

Regards,
-- Al

Along with the amp I would imagine speaker cable selection would be critical as well?

Yes, that's true, Rja. Speaker cable effects will tend to increase as speaker impedance goes down. Atmasphere among others has made that point in some past threads.

Since it seems that speaker cable effects can't be entirely explained or predicted technically, at least in a manner that stands up when analyzed quantitatively, it's hard to give a complete explanation for that, however.

But among other factors that may be involved, resistance and inductance (or more precisely inductive reactance, the inductive form of impedance) assume greater significance in relation to speaker impedance as speaker impedance becomes lower. Which increases the consequences they may have as a result of the voltage divider effect.

Likewise for the rise in resistance that occurs at high frequencies as a result of skin effect, although whether that may be audibly significant under most reasonable circumstances is debatable. Also, although again its audible significance is debatable, lower speaker impedance is likely to worsen the mismatch between speaker impedance and the "characteristic impedance" of the cable, which will to some small degree affect inductive and capacitive energy storage in the cable, and waveform reflections and RFI pickup that may enter the feedback loop of the amplifier, if it has one.

There are probably other effects that are involved as well, but those are a few possibilities that come to mind.

Best regards,
-- Al