That is one beast of a receiver. The one I bought new in the 90's is still going strong as my primary rig powering Canton CT 1000 speakers of the same vintage. The actual output is approx 100 watts per and you can not beat the transparency of the music it puts out. I have a spare on the shelf I bought on ebay years ago for under a hundred because you can not find anything new for under a grand that is a clean and pure as the Nak R1. I drive mine now with a Meridian Explorer USB DAC from my computer using Music Bee against my iTunes library to avoid iTunes artifacts. R1, RE-1, and reciever one are all different animals. It's very hard to find info on the R1 compact setup.
This 'How-to' video from our Product Support team will supply you with the information you need for.
I also have the unit with cd/cassette module and remote. I was looking for a compact setup for my niece and I think I overpaid at $95. It might need some work on the amplifier section because it got muddy and distorted at any appreciable volume even though I think it's rated at 30wpc.
Ironically this little guy has pre-outs.so I tried it through my HK 870 and of course it could rock the house lol. Here's a link to an AK thread about the R1 but I still can't find any specs or a manual for it.