Current optimized or voltage optimized speakers?

Couldn't have said it better than Michael (Swampwalker) did, except that in the last sentence change "wattage" to "voltage."

Also, although it doesn't directly relate to the question, it's worth mentioning that Ralph (Atmasphere) has also stated that solid state amps, as well as tube amps, will generally perform better into high impedances than low impedances. This assumes, of course, that they are not asked to approach the limits of their power capability when doing so.

One final point, although it is a fairly obvious one. Researching what amplifiers others use with a given speaker can often be helpful in determining whether to go tube or solid state.

Best regards,
-- Al

Impedance phase angles which are severely negative (i.e., capacitive), especially at frequencies where the magnitude of the impedance is low, will make life difficult for the amplifier in terms of how much current it has to supply. Also, the efficiency of the speaker will most likely be less than it would be if the phase angles were more benign, everything else being equal. That will further increase the power demands on the amplifier.

I don't think, though, that highly capacitive phase angles in themselves are necessarily an indication that a suitably high powered tube amp would not be sonically compatible. Although, of course, high quality high powered tube amplification does not come cheaply.

Best regards,
-- Al

Bruce, keep in mind that there are many shades of gray in between the black and white extremes. And that applies to both speakers and amplifiers.

While there are some speakers that will clearly be mismatched when used with one or the other kind of amplifier, tube or solid state, there are a lot of speakers that will do reasonably well with either. In those cases, the two resulting presentations will certainly have different sonic characters, but the differences will be such that room acoustics, personal taste, and the intrinsic sonic characteristics of the particular amplifier will determine which is preferable.

And while ALMOST all solid state amplifiers will fall into the voltage paradigm category, tube amplifiers will fall into the power paradigm category to varying degrees, depending primarily on their output impedance (output impedances for 8 ohm taps being equal to 8 ohms divided by damping factor), and its relation to the impedance of the speaker that is being used. As a general guideline, which is applicable to the kinds of damping factors that are most commonly encountered (i.e., those greater than about 2 or so), and to the kinds of speaker impedances that are typically encountered (i.e., nominal values that are in the 4 to 8 ohm area or thereabouts), the lower the damping factor (or equivalently the higher the output impedance), the greater the degree to which the amplifier will behave in accordance with power paradigm principles. (That guideline but may not be applicable in some extreme situations where the numbers fall outside those limits). ARC amps tend not to be as far into the power paradigm category as a lot of other tube amps, I believe mainly because their use of feedback tends to result in lower output impedance.

Take a look at the impedance curve of the Harbeth M40.1. It fluctuates all over the map, yet that speaker is widely used very successfully with tube amps having significantly lower damping factors than yours.

I believe a Power Paradigm amp (tube) will put out the same wattage regardless of impedance peaks.

No, it won't eliminate variations in power delivery as a function of load impedance. What it will do is to REDUCE those variations, in comparison with a solid state amp. The degree of reduction will depend on the relation between the output impedance/damping factor of the particular tube amplifier and the impedance characteristics of the speaker.

But if I was starting from scratch and already owned the VS-115, should I have looked to match my amp with a different type of speaker; and vice versa, if I already owned the S-8s, should I have looked to match the speakers with a different type of amp.

I think that's the bottom line Q here. How does one make an informed decision?

We had a related discussion a little under two years ago in this thread. For comments that are specifically relevant to your situation, see my two posts in that thread dated 1-5-11.

Best regards,
-- Al