Yes, the naks are powered by a round 9v that can be purchased at Rat Shack. A lot of them come in 3's since they were also sold that way back in the day. Also, the Nakamichi MX100 pre-amp had inputs for L, R & center. I only have a pair, but Mark that I mentioned above has 3, but normally only uses 2. Ebay is hit or miss w/ the Naks as far as pairs or set of 3's go. There were some in the yard sale a week or so ago.
Feel free to ask any other questions.
Jim
+T for the upgrade bug.