That is just a horrible location for a sound system. The walls are just too close together.
If you must change the port, you will have to side port them on the inside wall panels. I don't think there is enough room for a port on the front panel.
That will mean removing the current port and completely sealing up the holes. You will have to remove all drivers and drill the holes for a new port of exactly the dimensions as the old.
Quite honestly though, that horrid little cubby hole does not merit a sound system. I would find another location, even if it is another room.
Basically audio and AV system bring enormous pleasure, and you wife needs to understand that audio and AV systems do not really detract from the decor. Homes are not for view, but to be lived in and enjoyed. A big part of the enjoyment for many is getting the best out of audio and AV systems.
Your wife needs setting straight.