Re: attenuating amplitude of a signal
You can buy ultra-low noise metal film resistors (0.1% Tol) from many vendors. Also important is to keep their values to under 100 K ohms. You need a 1000:1 divider, and for precision you may need a trim pot. 100 K and 49.9 ohms is 2000:1. Insert a 100 ohm trim pot between them to get an exact 1000:1 ratio.
Adding op-amps will add noise and offset, and power supply issues, so if passive resistors will work then go simple on this.