oh, OK. I think I remember getting something like this with my Starmate 5, but I was able to connect it directly to an AUX port in my Odyssey so I have nice clear sound & had no use or didn't worry about this "power connect" option.
My original Starmate Replay and Xact XTR3 units have great FM transmitter, but these are pre-FCC mandated models. I use them for the house only with home dock kits & am able to broadcast the signal to various fm radios in rooms on the main floor and in the basement. Just for kicks, I did happen to try the FM transmitter on the Starmate 5 and it is pathetic. I know the reasons (FCC mandated) for the poor quality, but I thought this was pretty useless. I guess this 'power connect' option helps solve this problem if needed.
In case I am in a situation where I would need to use the 'power connect' option in a car, how good is this approach? I know its probably not as good as an AUX connection or using an FM modulator antenna adapter, but hopefully its a LOT better than the current built-in FM transmitters & still curious how their quality has been.