I have one of those GRE amps. I use it inline with a notch filter to the frequency range I want to RX. If I turn it near half way it wipes things out. It just raises the noise floor too much. (Of course, the noise around me is not the same for you)
I have to keep the dial set at less than half. Also, without the notch filter, it almost wipes everything out unless I turn all the way down or off. Basically, I have experienced the same result you are with that RX amp. It simply overloads various wide band RX equipment, or at least my receivers that cost less than $1000.
I actually have two of those, they both operate/have the same result. Hmmm...now that I think about it, I have never used it down low on HF frequencies so I am unsure the results there; however, as to VHF and UHF forget it...unless you employ a notch filter or a narrow tuned antenna.