I use the Hab/Nevis/Uputronics amp with a cavity filter between it and the antenna or the rtl-sdr amp(again with cavity filter). I have so much noise in my area that I need cavity filters. I must test the airspy with just the rtl-sdr amp/filter without the cavity filter some time. I remember testing the hab/nevis/uputronics amp years ago and it had to have the cavity filter(using rtl-sdr, airspy or radarcape). I have heard reports that the rtl-sdr amp/filter is a bit better in noisy environments. I may be able to put the cavity filter between the airspy and amp. They are close enough I can run a USB cable to power it.