Speaker and amp compatibility


I have a Rogue Audio Sphinx v2. I am looking at a used pair of 
KEF 104/2 Reference Floor-standing Loudspeakers

They are 4ohm with a max 200 watt.

The rogue puts out 200 at 4 ohms. Is that sufficient or would I need more power. I am a newbie and this is probobly a really basic question for you guys.

Thank you ahead of time
Charles
cpdkee
These speakers are rated at 92db sensitivity. You should be more than fine.
The speakers handle at most 200W, and the amplifier will put out 200W before distorting heavily/reaching its limits, but you're unlikely to actually listen at levels that need 200W. The KEF 104/2 has a sensitivity of 92dB @ 2m @ 2.83V.

Assuming the Sphinx V2 has enough drive (the speakers are 4 ohms nominal, which means they may dip lower, and they may also have some difficult phase+impedance points), you'll probably only use a few dozen watts at the most unless you are sitting very far away or are trying to damage your hearing.
One quick note - don't judge the power you are using by the position of the volume control.  The knob position does not correlate directly with output power.  At the hallway point, it could be putting out 50 watts,  watts, 100 watts, 28.7 watts, etc.  Many amps have high input sensitivities, so they go really loud early in the volume control range.  It makes you think you've got a really powerful amp, but you can run into clipping before you get anywhere near the top fo the volume knob rotation.  
KEF 104/2 are a fairly benign load.  Your Rogue should be pretty happy with that type of speaker.  Hopefully the KEFs come with the Kube that goes into the low level signal loop. 
I was going to say those old wooferS in The box KEFs rolled off a cliff after 50 hz without the kube, but since everyone uses subs these days no big deal 
I will add that if the OP want's to take full advantage of the 200 watts, that cotton in the ears are advisable. That is to keep the blood flow ... from getting on the clothing.