Sorry if this is a dumb question
Do you need a seperate power amplifier for these?
Such as the Line 6 Pod HD X, or the AXE-FX
Yes for the most part. There is a Kemper which has one built in, and also the DV Mark one has a power amp built in, but the Line 6 stuff and AxeFX models have no built in power amp.
Obviously you could use them with powered speakers and the like, but they have no way of driving speakers on their own.