Rather than sitting still during challenging economic times, premium earphone maker Ultimate Ears has released its most affordable custom-fit headphones to date, UE 4 Pro ($400). Cosmetically near-identical to the company's considerably more expensive UE-10 and UE-11 models, as well as the company's prior mid-range versions, UE 4 Pro features two drivers per ear rather than the three found in UE-10 and UE-11. It also features the silver UE branding…