If it is a coin toss...
I would choose Wadia if you listen to classical music. It has the ability to pull out the detail of professional musicianship, the textures and layers from the composer, and the subtle nuances in balance and rhythm from the conductor. It also presents a realistic soundstage that makes a believable representation.
I might consider EMM if you listen to jazz, pop, and rock music. I don't feel those genres benefit as much from high resolution. The EMM may have some warmth that is needed for many popular recordings.
For classical music, I keep on coming back for the details. That is why I have 15 recordings of Mahler #2. If you like jazz and pop, the details are interesting, but does not sustain itself.
I seriously doubt that the max output on the Wadia would not readily play at an unhealthy level of loudness. Perhaps you know something I don't though.
In terms of Wadia with pre vs. no pre, there is no firm consensus. If you go without a pre and only have a single source, then you need to invest in a proper platform, power cord, and consider a modified unit.
