As product manager, I've helped develop the product and have over 4 here. They all exhibit this, and this is normal. With 87.5dB efficient speakers, I have to be within 1 foot of the speakers to hear it. Bare in mind, the signal level is low so how efficient your speakers are, how close you are, how good your hearing is, and how easily driven your power amplifier is will all determine if you hear this. Regardless, it is there.

P.S. The volume control of the pre-amp also impacts this. With the Model 7000x being fed by the Model 976, a foot away with 87.5dB speakers, I personally can't hear it until about -20dBFS. I can hear it from about 2.5 feet away when the volume is maxed out. If there is any room noise, I would be impressed if you could hear it. To ensure you are not hearing any audio from the headphones, or mistaking it as audio from the headphones, you can simply plug in a 1/4 adapter to switch the pre-amp into headphone mode.