In 1971 I bought one of the 500/M Hofner violin deluxe models with the full array of music mix controls. The instrument was made of their best blonde woods, a 3 or 5 pieces neck, I can't recall, ebony fretboard with double dots, gold plated hardware special MOP inlay on the headstock.
The instrument had a 9-volt battery fitted into the back of the instrument under a gold plate. There was a toggle switch on the upper bout to shift between pick ups. The black control panel on the lower bout had more knobs and switches than I can remember. There was a volume and a tone knob, I know there was a bass boot switch (which was insane) and I believe there may have been other flick switches.
Hofner's idea was to produce a deluxe blonde instrument with more controls so that one could mix the sound over a borader spectrum to meet your needs.
I now own a Hofner Ignition bass and love it. So, forty two years later, I use either Hofner/Pyramid strings, or T-I Jazz ROUNDwounds on the Ignition bass, and can get all the sounds I need.
Currently, there is one for sale on e-bay: http://www.ebay.com/itm/Vintage-Hofn...item3cd5cc224a