That's interesting, and I sure can hear it. I haven't bought an EMG preamp since the mid 90s. Maybe they are noisier now?
Here's an EMG BTC in one of my basses with my ND3 neo pickups. It starts off passive and then at 31 seconds you can hear me switch in the preamp. I then go through the pickup combinations again. Later in the clip I crank up the treble all the way. This bass (the one in my avatar) was built in 1994, and had the BTC in it since that time, and originally with active EMG pickups. I no longer have the preamp, as I sold the last two I had. The current owner of both hasn't complained about noise.
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You can hear that I'm not getting any hiss except what the mixer is adding, which is very slight and present in the passive section of the clip. This was recorded direct to a Roland VM-3100Pro digital mixer.
They must have changed the op amp they use.