Greetings Spaceboy.
As Graham put it, Yes...if you wish to achieve the best possible sound, but absolutely necessary...?? No.
I do most of my mixing on-board and monitor via (2) Klipsch KG-2's. These are a home stereo speaker, not studio monitors, but the sound is clean enough that monitoring and editting are no problem. I use headphones for scrubbing, but not for final mix-downs.
What am I using for a Power Amp??
A very old, and very reliable, 45w (x2)
Onyko. I also have a 30w Pioneer as a back-up.
You don't really need to break the bank, setting up your home system.
Good Luck Cowboy.