I have the DigiTech JamMan Looper, and I find it to be hugely noisy... so much so that I had to ditch it.
You also said that you have two amps... if you are using some sort of A/B box to play with both amps, there is the possibility that you have created a "ground loop", which will cause a large amount of noise. Fulltone has a wealth of information on this subject.
It is also beneficial to use a power supply with independent, dedicated jacks, such as the offerings from VooDoo labs. If you are using just a regular daisy chain connection for all the power supplies, there can be some noise from that too. I found that even with my looper plugged in to the power supply, but not in the signal chain, it introduced some noise.
"Learn as if you were to live forever; live as if you were to die tomorrow."