I wonder if you could expand on what you mean by ’ohm tap’ and which amp would be best in that regard with the Sabrinas?
Rinpoche, most tube amps drive their outputs via a transformer, which converts the high voltage/low current signal that is processed by the tubes to a lower voltage/higher current signal that is needed to drive a speaker. Usually at least two transformation ratios are provided (i.e., how much the voltage is stepped down and how much the current is stepped up), including one that is theoretically best suited for 4 ohm speakers and one that is theoretically best suited for 8 ohm speakers. Those are provided on different terminals on the rear of the amp, and are referred to as "taps" because the terminals are connected internally to different points on the output "winding" of the transformer.
The 200iq provides a third tap, theoretically best suited for speakers having even lower impedances.
The circuitry in nearly all solid state amps operates at lower voltages and higher currents than the circuitry in nearly all tube amps, so most solid state amps do not need or have output transformers, or multiple output taps.
If you click on the photo of the rear of the 200iq, shown on
this page, you will see that their are a total of 8 binding posts/terminals, 4 for each channel. For each channel, one wire from the speaker (usually the black or negative one) connects to the "Com" terminal, and the other wire from the speaker (usually the red or positive one) connects to one of the other 3 terminals, corresponding to the chosen tap.
Since most speakers have impedances that vary significantly over the frequency range, a nominally 4 ohm speaker will not always sound best when connected to an amp’s 4 ohm tap, and an 8 ohm speaker will not always sound best when connected to an amp’s 8 ohm tap. It is often best to try each of the taps that are provided.
The impedance curves I have seen for several Focal speakers all show a substantial rise in impedance occurring in the upper mid-range and/or the treble regions. Throughout most of the spectrum your Sabrinas also have an impedance that rises considerably as frequency increases. The interaction of relatively high amplifier output impedance with those kinds of speaker impedance characteristics will result in a brighter sound than if the amplifier has a lower output impedance, everything else being equal. Output taps on a tube amp that are intended to drive lower impedances (e.g., 4 ohms) have lower output impedance than output taps intended to drive higher impedances (e.g., 8 ohms). Solid state amps almost always have effective output impedances that are near zero.
So that probably explains why you perceived some brightness with the VAC/Focal combination, and I suspect explains why Knghifi perceived some brightness with the combination of the 200iq and the Sabrina (especially if the 1 to 2 ohm tap was not the one that was being used). The brightness was not the result of the amp’s intrinsic sonic characteristics, but rather was the result of a non-optimal impedance match to the speaker, which would be minimized (although perhaps not entirely eliminated) by using the 1 to 2 ohm tap that is provided on the 200iq.
As far as power is concerned, considering the sensitivity of the Sabrina and the power capabilities of the VAC amps, as I mentioned early in the thread I suspect that if you were to have a problem it would only be on recordings having particularly wide dynamic range (i.e., particularly great DIFFERENCES between the volumes of the loudest notes and the softest notes). Some well engineered minimally compressed classical symphonic recordings come to mind, such as many of the Telarc orchestral recordings from the 1980’s that were notorious for having very high volume bass drum beats. On most recordings, and **perhaps** even on those, I don’t think you would have a problem, though. This assumes that your listening distance, room size, and volume preferences are not significantly greater than usual.
Best regards,
-- Al
