Simple answer "you ain't supposed to do it that way, but you might get away with it". I did it once as a test, for a minute, and nothing fried, although I'm not going to say it's a good idea. I used spare CM100 bodies which I have, although that's as far as I took that little experiment.
Where I'm going with this... is that if you have a set of Nak 300's I will gladly loan you my CM100 bodies, and you can run them CM300 heads > CM100 bodies > cable > CA9100 > recorder for a test. If anything is going to fry on the Nak end, it will be the transformer in the bodies, and if that happens I won't hold you responsible. I'm willing to take that chance for the advancement of taper science.
On the other hand running 9V from the CA9100 into the Nak transformer is essentially a dead short across the plug-in-power circuit of the CA9100. I'm not sure if the preamp will stand that for very long. Chris?
Nak CM-100 bodies look identical to CM-300 bodies except they have a little different electronics buried inside. You can screw CM300 attenuators into CM100 bodies (they fit) and run them... I've done it, although they don't sound quite like "proper CM300s", and they have less gain than regular CM300s:
http://www.archive.org/details/raq2007-04-22.nak300.flac16fNaks don't have much output. I've run Naks > R-09 using mic high gain, with mediocre results. Running line in will not have enough signal.
Another option is the cheap Nady DMP-2 preamp.
http://www.archive.org/details/gptn2007-08-18.nak300.flac16f