David wrote
I was wondering, I am planning on using my HiFi speakers with my PC, I
have heard that I need and amplifier to make them work, will the base
unit that the speakers were originally plugged into for the HiFi
system work and them pluggin that into my Sub?

You have a powered (active) speaker system with a sub and main set of speakers
that you want to use with your computer?

If yes, then you can use it with your computers soundcard and or headphone
output but the output will need a gain stage (something like a mixer) to bring
the level up to the power amp(s) in the speaker(s).

You can use a stereo reciver or a mixer to do this, it just depends on what
(make, brand) equipment you have.