Here's an SB7 session I did with the spirit box plugged into my guitar amp with reverb turned up. Got better responses than I ever have. I get a girls voice come through that I recognize from many of my recent SCD-1 GhostHunterApp sessions.
Note: If using a bag or faraday cage to block signals. I tested this a few more times with an external speaker. Seems the wire turns into an antenna and lets through some signals, also works better with some electrical tape covering the antenna to prevent it from touching anything that helps it get a signal.