Minimum recommended amplification requirements and amplifier matching


If a speaker has a "recommended amplification requirement" between 80W-200W with a 90dB sensitivity what are the actual minimum amplification requirement? In particular, the Line Magnetic 211ia is rated at 15W triode and 32W ultralinear. Can smaller tube amplifiers provide enough wattage to drive speakers that require more than twice the recommended output?
ddemilto3
You mentioned in your 12:16pm post "...all other things being equal". Am I correct that you are also speaking of the *sound pressure level*? I ask because if so, again it would seem to me that higher speakers impedance (say 16 ohm instead of 8) would mean that one would need to raise the volume/power to achieve the same SPL, and hence in so doing could increase distortion if the amp is not operating in its "comfort zone".
The 'all other things being equal' is meant to suggest that if you could magically have the same exact speakers, differing only in impedance.

16 ohm speakers do not need more power. Impedance and efficiency are two different issues; a watt into 4 ohms is the same sound pressure as a watt into 16 ohms 'all other things being equal'.

If you are used to the sensitivity spec rather than efficiency, then the 16 ohms speakers might seem harder to drive. This is because the sensitivity spec is based on voltage (2.83 volts) rather than power (1 watt). Into 8 ohms the two are the same; into 4 ohms the power is 2 watts if the voltage is the same, and into 16 ohms the power is 1/2 watt if the voltage is the same.  This can make the higher impedance speaker appear harder to drive, but if we are talking about tube amps, they are no different; in fact quite often a tube amp will make more power into 16 ohms rather than less.
I asked this question in another discussion but this one suits better.

If a speaker manufacturer has the following specs; do they mean the recommended power in 8 ohms or 6 ohms?

Specs:
Impedance: 6 ohms
Recommended power: Minimum 50wpc

If a speaker manufacturer has the following specs; do they mean the recommended power in 8 ohms or 6 ohms?
Neither. I'd imagine the particular speaker manufacturer is providing a spec for minimum amplification because they are wanting to avoid clipping, which occurs more easily when lower powered amps are driven hard (played loud).  

Thanks @gdhal 

So, if I buy an amp for my 6 ohms speakers with recommended minimum power of 50wpc and if the amp has a power of 50wpc in 4 ohms and 25 wpc in 8 ohms. Am I meeting the "technical" recommendation?

I know what matters is whatever sounds good to us regardless of the specs (as long as you do not know want concert levels in your room) but I am just trying to learn the technical aspect of it.