Minimum recommended amplification requirements and amplifier matching

More importantly, can you audition those speakers with your amp?    Specs are great but don’t always tell the whole story.  I was driving a pair of 87dB eff speakers with a 40 watt el34 amp and it was plenty loud for me in a 17 x 15 x 9 room.   Current speakers are 99 dB eff and it’s ridiculous with just 40 Watts.  

+1 lowrider,
Impedance, not sensitivity is a more important value.
Should your speakers dip below 4 ohms, you little amp is going to have a hard time keeping up.
When in doubt, call the manufacturer.
B

+2 @willemj , agree completely. 
I used a 300W/Ch/4 ohms with Monitor Audio Silver 8s with good results.

I tried a Line Magnetic with an older Gallo speaker 4 ohm 90 dB sensitivity.  It did not work well at all.  I concur with the other posts.  It’s the impedance not the sensitivity that matters.  Line Magnetic does not like low impedance speakers, but check with the distributor, Tone Imports.

I once drove a pair of monitor audio silvers with EKCO  integrated.  This is a very good tube amp indeed but with this pairing in triode the bass was very bloated.  Much better in UL mode.  I really wonder if the MA silvers aren't better off with SS gear. (Having said that I sold this to a gentleman who was very happy with this amp paired with guess what--Monitor Audio!)  Just be aware the pairing is critical.  It's often not the power that's the issue as much as the complexity of the load a given speaker presents to a tube amp--especially in triode or SE designs.  UL with a bit of negative feedback will be more predictable.