Shortwave Gold on 6160 is well on 6160.00, maybe 6160.000 within 1 or 2 Hz,
you can'tb expect better with Doppler effect.
Use that to check your receiver frequency reading.
Kiwi SDR's with GPS reference are 'spot on', except when they are lacking of enough GPS signals.
Kiwi SDR's without the FGPS reference are often 40 to 60 Hz up or down from the exact frequency.
If reading 6159.96 instead of 6160.00, use the 0.04 difference for all the other stations around.