Watts and power

listening99,

Unfortunately, I could not find much in the way of testing of the STA200, and as you probably know, the marketing literature is very sparse w.r.t. details.  There is this test on AudioScience    https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-nuforce-sta-20...
... which is all done into 4 ohms, and other than fairly high mains noise, nothing looks off. Since you have not mentioned an issue with your likely highly efficient horn loaded speakers, that does not appear to be a problem, but if the Tekton Moab's are a lot more efficient than what you have now, that could be a problem.

Take the comments made by the "reviewer", AMIRM, with a grain of salt. He is the type of "measurements" person, that gives other people who believe in measurements a bad name. His comment

"Looking at the power rating versus distortion, the STA-200 doesn't bring much to the party over the much cheaper Topping TP60 ($199)"

...  shows a lack of knowledge/experience w.r.t. what is important. At low power levels, where almost all music is, the STA200 has much lower THD than the Topping TP60, and considerably lower IMD. The STA200 though clips really hard w.r.t. IMD. With the really efficient speakers, hopefully you won't run into that issue.

Tekton is usually conservative in their impedance ratings. When they say 4 ohms, it usually will not dip much below 4 ohms. I would say you have little to worry about other than what is stated above.

The Nuforce is stated to be suited to 8 ohms, not 4. The Moabs are efficient, running at a rated

• 98dB 2.83V@1m sensitivity

If the speakers run easy, what am I doing to my 8ohm amp, were I to hook them up...?

If you were playing two 8 ohm speakers simultaneously, then the resulting impedance of both together is 4 ohms. If you then expect to play one 4 ohm speaker and one 8 ohm speaker in the same situation, I would check with Nuforce before proceeding as two such speakers in parallel will be 2.8 ohms.

The idea is to replace my existing speakers with two speakers that present 4ohms resistance/each. I understand the speakers are efficient, although the manufacture statistic of 98dB is probably overstated. The hope is that the amp functions well at the lower volumes I would listen to, habitually. I mean, if a speaker can produce 90dB with less than a watt of power, I should have very little difficulty, sitting about 8-9' away, and then the amplifier is basically loping along, even with two 4ohm speakers, right? I keep hearing the Moabs are amazing and no one is complaining about the 4ohm load... 

@listening99  Two 4 ohm speakers in parallel is 2 ohms.

You really want to check with the amp manufacturer to see if its OK with a load like that! But generally speaking, the lower the load impedance, the higher the distortion of the amp- and that will manifest as harshness and brightness. After spending the kind of money that high end equipment costs, this (to me) simply seems like not servicing the speaker or amplifier investment $$$$ very well.