Harry, K9HDT, posted a message in the Eton E5 Yahoo group about his E5's power adapter. He said that his adapter was causing interference and adding noise to the audio. After contacting Eton, he was offered a replacement adapter.
I located my E5 adapter and plugged it in to test it. In the shortwave band, my E5 has a much higher noise level compared to running on battery power. No problem was observed with the mediumwave or FM bands.
I asked Harry a couple questions about his conversation with Eton. After he replies, I will also contact Eton to request a replacement adapter. Other E5 owners can comment here or in the Yahoo group if they experience the problem.