[ryandrake]

Two separate USB RTL-SDR dongles. Very important if you do two receivers: Make sure you have an official Raspberry Pi 2b charger that outputs enough wattage. Cheesy bargain bin power supplies you get on Amazon are not up to the task of powering the Pi + 2 radios, and they will not work. Get some good airflow around the radios too, because they can get a bit hot.

[ProllyInfamous]

I've been really disappointed with the Cannakit power adapters which came bundled with my 3b+ units (four, total). They are definitely not able to deliver enough power to even a dongle-less Raspberry – not sure why they were paired together.

All have been replaced with beefier AC/DC bricks. Definitely thanks for the consideration and model reqs.

My own recommendation is to use a powered USB hub, immediately plugged into any Pi (so the Pi's adapter can just worry about powering only CPU board).