Hi, First GQRX uses gnuradio, so I assume you meant GRC in the sentence above. That patch is just not correct. It would map two distinct gain control to the same gain stage ... BB gain is not MIX gain, there is no BaseBand gain stage on the airspy. To set the gain stage in GNURadio for the airspy you need to use the named gain stages setting API but because this API uses run-time discovery of available gain stages, and that's not easily doable in GRC using only the 'gui' stuff because you need to actually _call_ a function on the gr-osmosdr block to update it. That's doable using the function probe in theory. The 3 "boxes" ( RF / IF / BB ) that are by default in the GRC property are just historic shortcuts from before it supported a full named gain API. The best solution would just to have a new GRC block (or two, one Qt, one WX) that automatically discovers all the gain stage at run-time and makes a slider for each of them just like osmocom_fft does since it's often what people want to do. And this way it auto adapts to whatever SDR is detected at run time which is kind of the point of gr-osmosdr. Or several entry box in GRC each time with the name of gain stage to control and the value to set for the case where you want manual control. Something like "Gain 1 Name:" "Gain 1 Value" "Gain 2 Name" " Gain 2 Value" ... Cheers, Sylvain