Hi SylBer,
As Kcarlile pointed out, the in-cabinet M80 has front-mounted ports, but it also has a front baffle that protrudes slightly from the cabinet into which it is mounted. The sound quality is essentially identical (I do the listening tests) and the slightly protruding front baffle is done to remove the adjacent boundary effects that would otherwise skew the response if the M80 were completely flush-mounted. The depth of the cabinet and internal volume is identical to the standard floor-standing M80.
http://www.axiomaudio.com/m80-in-cabinet.html Regards,
Alan
