Problem is that speaker manufacturers never gives the whole impedance facts/measurements/charts. Tha’s why generalizations to say 8 ohm speaker spec means almost nothing. I choosed at random ( between hundred of ST measurement. ) and you can read there that your words are not exactly rigth with some of those speakers, same for maplifiers.Whenever anyone asks if a speaker will work with our amps I take a look at the impedance curve if one is available. But if the speaker is rated 8 ohms or more I pay attention, and if the speaker is rated higher, like 16 ohms, I’ve yet to run into one that didn’t work. I’ve seen some speakers, like B&Ws, that are rated ’nominally 8 ohms’ but feature dual woofers, which are wired in parallel, although the midrange and tweeter array is certainly what I would call ’8 ohms’. The woofer array, even though it may have peaks at 8 ohms or higher, is something I would regard as more of a 4 ohm load. So you do have to be careful about this issue; but in the case of higher impedances it usually no worried at all.
The Sound Lab is not a speaker rated at 16 ohms or 30 ohms despite both impedances being present at some frequency. While it is difficult for most solid state amps to make power on this speaker owing to the 30 ohm impedance in the bass (which is why a tube amp of 150 watts can easily keep up with a solid state amp of 600 watts on this speaker), all this means is that you might see about 1/4 the power the amp is rated for into 8 ohms. However, and this is important, as the frequency goes up above about 5-7KHz, the impedance is dropping, to a low of about 1.5-3 ohms (depending on the setting of the Brilliance control) at 20KHz. Like almost any full range ESL, the impedance varies by about 10 or 9:1 from the bass to the highs. The issue here is that a good quality solid state amp will double power as impedance is halved. With a box speaker, this is fine because a peak in the impedance curve usually represents a resonance so this property is welcomed. But this isn’t the case with the Sound Lab. It needs about the same power in the bass region as it does in the high treble region to make the same sound pressure at that frequency. This means that an amp that can double power (and the Sound Lab does not challenge most solid state amps in that regard) will be excessively bright due to this property.
To get around that issue, the Sound Lab is equipped with a number of settings to modify the speaker’s response. The Brilliance control is there to deal with excessive brightness, the bass settings allow you to boost or cut the bass, depending on if you have a solid state amp (boost) or tube amp (cut). IIRC there are midrange settings too.
One nice thing about this speaker if using solid state is that the bass impedance (where the power is) is high, resulting in low distortion for nearly any amplifier. Low distortion means less harmonics from the bass notes, so an amusical harmonic like the 7th, 9th, 11th or 13th to which the ear is keenly sensitive, will be greatly attenuated. IME this is beneficial to all amps.
The mod that @lewm did seems a wonderful upgrade for the speaker!
