Here are some additional details about the DSA-815 series of spectrum analysers:
1) What is the output impedance for the earphone?
• Typically around 100 OHM (non-specified)
2) What is the output power of earphone?
• 10mW Output Power. But it is not guaranteed.
3) Is the earphone stereo or mono?
4) Is the demodulation stereo or mono?
5) What type of earphone jack?