A number of designs exist of preamplifiers to measure power supply, zener, LED, and other noise sources. These generally have a large input cap to isolate the source voltage from the input of the preamp. A large capacitor can have huge leakage, which can disrupt the input bias of the preamp.
Here is a proof-of-concept approach that doesn't use a large series input cap. Instead, the preamp input is direct coupled to the source. It uses a LT1028, which has an unparalleled low frequency noise corner and very low input noise.
The gain is set to 40dB. The low frequency response is determined by large electrolytics in the feedback path, but the leakage current of the capacitors has minimal effect on the output due to the design.
As in other approaches, multiple preamps could be paralled for very low input noise. The feedback resistors could be adjusted for minimum overall noise.
You can download the LTspice ASC and PLT files here: