SpeakON connectors are the ones that spring to mind instantly. (See http://www.neutrik.com/en/speakon/
The chassis connector will mount on a standard wall-plate which can be used with a back-box (standard electrical fixtures and fittings). Buy a back-box which is deep enough to accommodate the chassis connector and cable of course.
For a 70V line installation the 2-pole SpeakON connectors should be OK. Loop the cable from the amplifier to each socket in turn.
SpeakON connectors are pretty standard and have a locking mechanism which prevents the connector from accidentally falling out.
Use rubber grommets where the cables exit the metal back box to prevent cutting the wires over time.
You may also find this website useful: http://www.buyspeakercable.com/info_...onnector.shtml
How long is your cable run from the amplifier to the furthest speaker?