A typical 4 way non-amplified splitter will reduce the signal by about 7dB per output. How much signal do you have at the input? Can you "afford" to lose 7dB to each receiver?
I am using a non-amplified high quality TWO way "cable TV" splitter to split my discone to two scanners. I run another scanner on an RS800 because it is only receiving 800MHz and does just fine w/o the outside antenna.
However, I just installed several scanners for someone and because the loss was going to be more, I used
this amplified "splitter". I also added a band stop filter at its input to remove broadcast and other unwanted signals before amplification. (
4 way version)
You can't look at it that "more is better". You really have to know the signal levels you are dealing with (from the antenna), if there are any unwanted strong signals, and then if you use any amplifiers, make sure they are low noise and a good fit.