Sony MDR-DS6500 Operating Instructions Manual page 15

Setting the input level
If the volume is low using the analog input, set the ATT (attenuator) switch to "0 dB. "
Setting
0 dB
–8 dB
Notes
Be sure to lower the volume before setting the ATT switch.

If audio input to the LINE IN jacks is distorted (sometimes, noise can be heard at the same time), set the

ATT switch to "–8 dB. "
ATT
0dB
-8dB
Connected components
TV, portable components, and other components with a low output level
Other components (initial settings)
US
15
Connection