Spiritis Ghost box is my favorite. I hear my sounds from the ancients, like that of a large reptile—the only way to describe it.
Before I was a witch, I was a hapless person with a knack for communicating with the dead who was trying to figure out whether or not I was crazy. So I dove into paranormal investigation big-time. I used to be a lot more active, but my SP7 spirit box is still my baby. I’ve never tried it with demons, but it’s very reliable for work with the dead. You just have to train your ears to listen past the “blap” noises (cycling through radio stations with some loud bursts of voices or music) to hear the spirit voices. I remember once about to turn it off and hearing a very loud “DON’T” so not only does it work, but they know it works and want to use it!