Spec: My biggest concern about stepping up the voltage is the risk of getting power supply artifacts in the random signal. Last night I was doing some experimenting with a zener diode source, and after much amplification, I could see periodic spikes on the scope trace. It wasn't generated in my power supply, because it's a linear supply. So, it was some kind of external interference generated, and picked up in the gain stages. So, I can see that it will be critical to have everything well shielded and decoupled.