Here is the first APM loudspeaker : APM-9 !
Pretty similar to an APM-8... but different :-)
The "9" wasn't a prototype but a fully-functional and fully-finished pre-production item made when Sony still was aiming the (upcoming) "9" series at the professional market : broadcast & studio.
This explains the looks of the other 9s : PS-X9, TA-N9, EL-D9 and the (late) sibling PAS-70X monoblock. Sony however named its prototype SX-077.
Alongwith many pairs of TA-N9 monoblocks, APM-9s were used in the CBS studios as monitoring rig for many sessions.
Sony then changed its mind and went for the audiophile market - exit the APM-9 and the planned TA-E9.
I was told there are two pairs of APM-9 in France, still working and with no surround problems...
Large full-color images at last at hand for all this - not scanned yet.