Why Do All Arcam Units (and Maybe Others) Have Only Two-Prong Power?

Violating the ground of something designed to be grounded can kill you.  Just saying.

I could be struck by an asteroid too.  Did you try a two prong plug into the new place?  How did it sound?

Look at your toaster.  How many prongs does its plug  have.  A toaster would be a lot more dangerous to a user than modern amp.  

Violating the ground of something designed to be grounded can kill you.  Just saying.

I actually experienced the opposite.  I had two-prong outlets in an older home before building new.  When I ran my same system/amp again in the new place on a grounded circuit it was much better sound.

Because it sounds better.  A really easy test.  Purchase a three prong to two prong cheater plug and isolate your amp.  I actually use one for DAC also.  Much tighter bass and a clearer background.  There is a safety factor but your amp isn't a skill saw and to me the sound benefits outweighed the tiny risk of a shock.

Thank you for the answers.  I don't know why I never got a notification that there were any...

So is it possible for Class II units to have "fully balanced" topology inside?  Are Arcams?

Class II (with Roman numerals) refers to power supplies with either a double or
reinforced insulation barrier between the input and the output. Class II supplies do
not rely on an earth connection to protect against shock hazard. Many cell phone
chargers and laptop power supplies are Class II.
Many external power supplies are also Class II, having just a Line and Neutral AC
input without a ground connection.

A Class II power supply rating label will show this symbol:

Class II Class II symbol

A Class II or double insulated electrical appliance is one which has been designed in such a way that it does not require a safety connection to electrical earth (ground).

The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock and that this is achieved without relying on an earthed metal casing. This is usually achieved at least in part by having at least two layers of insulating material between live parts and the user, or by using reinforced insulation.

In Europe, a double insulated appliance must be labelled Class II or double insulated or bear the double insulation symbol: ⧈ (a square inside another square).

Insulated AC/DC power supplies (such as cell-phone chargers) are typically designated as Class II, meaning that the DC output wires are isolated from the AC input. The designation "Class II" should not be confused with the designation "Class 2", as the latter is unrelated to insulation (it originates from standard UL 1310, setting limits on maximum output voltage/current/power).