The A23 is an example. The (-) pin on the XLR input is grounded.
Erik, are you sure about that? From the manual
for the A23:
The Input Stage:
The A 23’s input stage uses matched pairs of discrete JFETs arranged in a differential configuration. JFETs are ideal for the input stage because their inherently high impedance is unaffected by the impedance of source components. Differential configuration provides superior noise reduction. These precision input JFETs are also cascoded to produce the current necessary to drive the MOSFET drivers in the following stage.
Also, while grounding pin 3 of an XLR input connector (the inverted signal pin) would be appropriate in many cases if that input were driven by a balanced output that is transformer coupled, or is actively driven but is "floating" with respect to ground, it could potentially cause performance problems, or conceivably even damage over the long-term, to some components having actively driven balanced outputs. (See this thread
for an example of a CD player that buzzed as a result of pin 3 being grounded by an adapter cable). Yet the manual for the A23 provides no cautions about the potential for any such issues.