To be honest with you, I have learnt about feedback and not about DC or AC feedback. Do you know any reference that makes this differentiation between those two types of feedback?
If you search for e.g. BJT biasing, (maybe AC amplifiers) or delve a bit into audiophile circuits/forums you will be able to read thousands of free pdfs, tutorials, app notes, etc. that explain both in the same document/page or separately. There wouldn't be time in the world to read them all .
For related things, I really recommend **broken link removed**, lots of informative and serious articles, and quite funny sometimes, I've learnt a lot of interesting things just having the patience to read through the ones of interest to me.
Earlier you were told that voltage negative feedback increases the input impedance and current negative feedback reduces input impedance. Then simply understand why:
1) Voltage feedback is to the emitter of the input transistor which has the same phase as the input signal, increasing the input impedance, since when the input signal voltage rises and drops then the emitter signal voltage also rises and drops.
2) Current negative feedback is to the base of the input transistor which has the opposite phase to the input signal so it cancels part of the input signal, reducing the input impedance, since when the input signal current rises and drops then the base signal current also rises and drops due to the cancellation.