I know nothing : Budget Under $1k

I am looking to move my 3.1 downstairs and add in-wall surrounds. I have an Integra 50.5 and am assuming that with the surrounds that now is possibly time to explore an amplifier.

I have $1k or less for this. I will consider used as amplifiers do not seem to have the curse of being outdated by different codecs etc.

I know this is fairly cheap for amplifiers.. but that's what I have.

It looks like in range there is an outlaw audio, emotiva, slightly out of range there is a Marantz. Other recommendations put below. Used I have no idea... the local store wants me to budget 3k for this which I just don't have...

Comments welcomed

all paradigm

studio 100 v5
sensitivity 93db/90db
amplifier range 15-350watts
max input power 230watts

prestige 55c
sensitivity 94db/91db
amplifier range 14-260watts
max input power 190watts

4speakers
ci elite
I80-
sensitivity 92db/88db
amplifier range 15-180
max input power 120