If you mean KEFQ100 or R100, they don't play very loud anyway so 100 WPC would be fine in a small room.
Something like the $700 Denon X3300H should do the job easily.
https://www.amazon.com/Denon-AVR-X3300W-Channel-Receiver-Bluetooth/dp/B01HL8KYAY/ref=sr_1_3?ie=UTF8&qid=1515162419&sr=8-3&keywords=denon+avr-x4300h
The equivalent Marantz would be the SR6011 but that typically cost more, perhaps due to the analog in features that few people use, or the hearsay of the so called "warm sound" going around in NA, that is false but people managed to convince themselves with the help of Mr. Placebo.
Both models come with Audyssey XT32 SubEQHT, you won't find that in any 2 channel receivers. As mentioned by others, a multichannel amp typically would have a larger power supply than a 2 channel version. That will benefit 2 channel use.
Base on the Audioholics review, the Denon should have all the power
into 4 ohms that your speakers would ever need, when used as a two channel receiver.
http://www.audioholics.com/av-receiver-reviews/denon-avr-x3300w-1/measurements