I tested the line in with 3 different sources. It seems it is made for a low level line in like an iPod. My CD player (Pioneer CD changer) and Panasonic BD player were too much for the line in and it distorted the sound. The iPod however sounds great, full and deep but I get a tiny bit of noise at high volume, silent parts.
Using USB from the laptop via the battery is very, very clean and silent sounding.
hi tim, was the Line-In set in low gain?