Assuming this was an original US piece, then 2 prongs is all you need, and you'll run into less ground loop / noise problems.
To use 2 prongs the equipment must be double shielded, so that an internal fault won't route the AC's 120V to the chasis.
I still use a shielded power cord however. This covers the AC wires in a shield that is grounded at the outlet and has no connection at the Luxman for noise reduction.
Most 3 prong cords are not shielded and cheap shielded cords are available on Amazon.
To use 2 prongs the equipment must be double shielded, so that an internal fault won't route the AC's 120V to the chasis.
I still use a shielded power cord however. This covers the AC wires in a shield that is grounded at the outlet and has no connection at the Luxman for noise reduction.
Most 3 prong cords are not shielded and cheap shielded cords are available on Amazon.