The brochure only says "Lancer’s wide 6.1” full colour display touch screen audio lets you immerse yourself in acoustics with Digital Radio (DAB), AM/FM radio, single CD player, iPod compatibility, USB inputs and Bluetooth® connectivity. Both audio and phone can be easily activated by voice or steering wheel controls."
Judging by that i would assume it's in-house as they usually state if it's a well-known brand like Rockford Fosgate etc. but it could also be exactly that, Rockford Fosgate, as they do a lot of OEM Mitsubishi sound systems.