After fighting with various USB audio input dongles and either having them be flaky or just not work at all with my raspberry pi I'm trying something new. I installed an RTL SDR dongle yesterday. It seems to pickup the approach frequencies on both the controller and aircraft side just as well if not better than the scanner I was using before. The only problem is getting bleed-over from SUS frequencies. The setup is in my hangar at SUS, less than a mile from the tower and I think the receiver just can't handle the power output from the transmitter at the airport. The RadioShack scanner I was using also occasionally had this issues, but not to the extent it's happening with the SDR. I might see if I can move it at a different location, farther away from the airport. In the meantime you'll hear STL approach and SUS clearance/ground/tower together. I'll be experimenting with some rtlsdr-airband settings but given the proximity to the transmitter I'm not sure there's much that can be done.
Geoff