I asked this question years ago. I couldn't find the thread. I went back to 11/14 in my posts and my eyes couldn't scan at anymore.
As I remember, the answer was that there was someone that was successfully using a 180W (10A) brick with an O scale DCC layout that was a portable layout that traveled to shows. The only reason I didn't go further with it was because that was the only person I came across that used that setup. I wanted a little more conformation.
I believe forum member AGHRMatt had some knowledge of that setup.