Analog input gain adjustment

Dear Mrs, For long I'm looking for a configuration option where I can adjust the gain/attenuation for the inputs in my Nad M10V2. My CD Player (audionet art g2) seems to have a "way too hot" output. Someone said on other posts "just use a 6 dB attenuator from Amazon", but somehow I'm afraid that might not be the same sound quality. So, there is a way to adjust the input level to better match my source equipment or I'll just have to find a way around with external attenuators?