What kind of antenna are you using?
Although you are so close, I doubt you would really need one for the 24's.
Actually I am feeding right now with a laptop.....and i only have a mic , no line in. Thats why it sounds so crappy.
I am feeding with an old laptop too, but mine has a line-in, and I am using that. The antenna is just a small whip attached to the BNC connector on the back of the scanner. It sounds much worse now that the laptop is connected, so I think I am just getting a lot of noise from the laptop. Same thing happened on my Burbank feed. That one sounds better now that I hooked up a twinlead J-Pole, but still not as good as yours.
I am going to make up another J-Pole and send it with my wife tomorrow. Hopefully that will help.