We have that model transformer, mounted in the engine room (next to our MultiPlus) so we don’t live with the noise.
The transformer gives a steady 100/120 Hz hum that is louder than the MultiPlus, unless the MultiPlus fan is running, then that is louder. We mounted it on isolation feet to avoid any vibration transfer to the hull.
Not sure how better to quantify it…
We have followed pretty scrupulously followed Amel’s rule that anything that made noise, generated heat, vibrated, smelled, or was otherwise unpleasant, lives in the engine room. In the case of the transformer, it made the wiring a lot simpler too.
Pittstown, Crooked Is, Bahamas