Well, you can't prove that the amp is bad until you've replaced it with something good, but in the mean time, you can take our word that the Radio Shack amplifiers are all bad news. The biggest enemy of digital TV reception, aside from distance, is noise. Any noise that your antenna collects is bad, and any amplifier is going to amplify that noise as well as create noise of it's own. RadShack amplifiers tend to inject a disproportionate amount of noise for the amplification they provide. With rare exception, they're junk; as good as snake oil in the days of analog TV, and pure rat poison in the modern age. Any amplifier also adds complexity and an additional point of failure in the system, and RadShack amplifiers are notorious for short service life compared to quality units by Winegard, Channel Master, and...Motorola...I guess. 
Splicer's right, without taking the mast down and removing the actual amplifier (so far you've only removed the power supply for the amplifier), your signal will not improve at all. I maintain that you don't need amplification, even for three TVs, at only 25-ish miles out. When you take the antenna down, unless you actually use the rotator, get rid of it, too. Again, reduce complexity and remove the extraneous points of failure. Maybe somebody on CraigsList will buy it from you. Also when you take the antenna down, replace the balun with a good one from Channel Master or Perfect Vision, just for good measure.
The troubleshooting phase is cheap; a couple of coax splices and a new balun will eliminate the variables for under $10. It's labor-intensive, though, and trips to the Emergency Room are never cheap. So for now, play it safe, but we're pretty sure that we know where your problem lies...
Splicer's right, without taking the mast down and removing the actual amplifier (so far you've only removed the power supply for the amplifier), your signal will not improve at all. I maintain that you don't need amplification, even for three TVs, at only 25-ish miles out. When you take the antenna down, unless you actually use the rotator, get rid of it, too. Again, reduce complexity and remove the extraneous points of failure. Maybe somebody on CraigsList will buy it from you. Also when you take the antenna down, replace the balun with a good one from Channel Master or Perfect Vision, just for good measure.
The troubleshooting phase is cheap; a couple of coax splices and a new balun will eliminate the variables for under $10. It's labor-intensive, though, and trips to the Emergency Room are never cheap. So for now, play it safe, but we're pretty sure that we know where your problem lies...
