That's a "bottom" cabinet for a bass guitar "stack". It usually would have been used with a 4x10" cabinet on top of it, for a "full stack", in a bi-amplified (lows to the bottom cabinet, highs to the top cabinet, from separate amp channels in the instrument amplifier/head) setup.
The Marlboro amps and speaker cabinets were originally sold by Montgomery-Ward's department stores- their equivalent of the Slivertone amps and speakers sold by Sears Roebuck and Co. Apparently, some people like these amps- for example, it is said that Audrey Creed of the Black Crowes used to use a Marlboro setup in early years...
In our specific case here- this is probably of limited use for "hi-fi" applications... the tuning is higher than any subwoofer, and the woofer is probably fairly high-resonance too...
Regards,
Gordon.