OpAmp: Better to actively attenuate, or drive full range into a divider?
Why in the world are you worried about Johnson noise?

Consider that the LM833 has a power bandwidth less than 1 MHz. Assuming your ADC has a 3 V input and 16 bit resolution, 1 lsb is ~46 µV. A 1 kΩ resistor with a 1 MHz bandwidth has a Johnson noise voltage of ~4 µV, and noise scales as the square root of the resistance. It would take a 529 kΩ resistor to give you 1 lsb of noise.

You don't say what your desired input impedance is. Let's say that it's 1 MΩ. You could use a 475kΩ/50kΩ/475kΩ divider network to get your input down to 3 Vp-p, followed by a simple unity-gain differential receiver, and still have &frac13; lsb of noise. And, of course, any lower value of input resistance will directly cause a lowering of resistor noise.

I really don't see the problem.