Do i need special connectors to view output on oscilloscope or i can just use the usual probes and connect them to headphone-out or line out of DSK (C6713)?
One exception are class d amplifier outputs. Here - to get a meaningful output signal - you should use a low pass filter.
The filter should pass audio frequencies and attenuate PWM frequency.
( I didn't read the datasheet of your device )
Ground loops may cause problems.. But I don't think it's very likely here.