Questions on next steps with my power amp

Well you have several things going on let's tackle them one at a time.
Your amp accepts what we call line level inputs. But your Onkyo does not have line level outputs. Your computer certainly does, and your CD player and tape deck probably do as well. But are they fixed, or variable? If fixed then you definitely need something (not necessarily a preamp, but something) to adjust volume. Your computer on the other hand definitely has variable output. In other words you can control the volume. So with probably just a phone jack to RCA adaptor you can connect the computer to the amp and enjoy music.

The turntable is a special case. CD, tapes, the signal they put out is already line level (line level simply means around one to three volts) and flat. With turntables however, the level depends on the cartridge and in any case always needs equalization. So for records you need a phono stage. Some really cheap record players have the phono stage built. Back before CD everything had a phono stage built in. Less common now but some still do. The best are stand alone phono stages.

Forgive me asking but a much bigger question is what are you doing buying an amp with no idea how or even if it can be used? If your goal literally is what you say, that you are looking to spend $1k, believe me, you don't need our help! But seriously, you could have a really nice system, the whole thing, complete soup to nuts and sounding really good, for one thousand plus the $649 that amp cost. If you shift the goal posts from spending, to being able to play music on a system you would actually enjoy listening to, I mean.

Wait, your 5.1 amp ..... is a pure amplifier, or an integrated or a receiver???

So I guess it may have been a bit naive of me to just buy an amp before thinking through the whole audio strategy but I heard a lot about this Outlaw amp and I have good speakers that I know I want a good power amp to drive so I went ahead and bought it. The tape deck and turntable I inherited from my father who recently passed away along with the Onyko receiver. I knew the receiver was not going to cut it. So I thought a pre-amp would be able to bridge everything but I haven’t been up to date on audio equipment in a while so that’s why I’m asking now. I’m a bit confused on DAC vs Audio Processor vs Pre-amp.

I have the resources to spend more than $1000 on the needed equipment. I just thought a music processor or pre-amp may be able to do most of what I’m looking for. In terms of playing digital music it doesn’t necessarily need to be directly from my computer but could be via my Samsung 10+.

Erik, the 5.1amp is a pure Power amp and not integrated.

Also in terms of the turntable and tape deck, I can buy new ones of each if I have to (ie like if i have to buy a turn table with USB connection). The main thing that’s important to me is that I inherited a huge record and tape collection from my father that means very much to me and I would like to play them. Right now I have my father’s 20 year old components that were good for the time (Denon tape deck and Sony turntable).

Appreciate the help all.

Or would it just be easier if I bought a new intergrated amp that would act as pre-amp/DAC? It's just that I'd rather spend more money to get a better sounding system and more complete setup.