Confusion about the meaning of floating
Floating is a voltage term and, like any voltage, it must have a reference. 

That is: "Object A can be floating with respect to object B."

If your shown circuit, both grounds are wired together, so the source, V1, is NOT floating with respect to the amplifier.

However, if this was a battery operated widget, with no other connection, the whole thing is floating with respect to the ground under your feet.







simulate this circuit &ndash; Schematic created using CircuitLab

The following schematic on the other hand has a floating source.







simulate this circuit

BTW: Just to confuse you further, there is a whole other meaning of floating.

In the schematic below the two inputs A, and B are unconnected and we call that floating. In this case they are actually tied to ground through the pull-downs, but the left end is still considered as floating whether the pull-downs are there or not.







simulate this circuit