Component recommendations: best bang for buck.

I just went through all this.  Maybe my thought process can help you...

1) get the cheapest surround processor with the features you care about.  If you don't need room correction, then an older unit will be great.  If you need room correction, don't worry about 4k processing.  Just run your source to your TV.  Get the connections you want.  Don't worry about whether it supports DSD/MQA/whatever digital audio because...
2) Get a separate DAC or even a DAC/Streamer with a built in preamp.  For price/performance it's tough to beat the Mytek brooklyn or the Benchmark DAC 3.  I recommend a separate DAC because digital audio is changing quite a bit now too.  That being said, this will be *fine* for almost all the audio you want to listen to.
3) McIntosh amps are solid pieces of kit.  Good quality, good resale, and (a little embarrassed) they look good, too.
4) Get the best speakers you can get.  I'm not a believer in expensive cables.  I'm a physicist...so you'll have a hard time convincing me that one piece of copper (or silver) is better as a medium for transporting electrons than another.  As long as it's properly shielded, you're good to go.  Don't spend thousands on cables.
5) If you have money left over, *then* look at nice stereo preamps, but after you pick the speakers/amp you want.  That will dictate output voltages and give you an idea of what works *in your system*.

I actually started with the speakers.  Bang & Olufsen BL5s.  Ended up with the Emotiva XMC-1 (none of the upgrades), and since I didn't need an amp, and I'm just using monoprice cables from Amazon, I had cash, so I stupidly lost my mind, blew my budget, and got a ARC Ref 6.  I had a nice CD player (BS9000) and just purchased an NAD M50.2 for streaming and digitizing my CD collection.  The only thing I'm debating now is whether to get a new DAC for the new digital formats, but I'm thinking the built in dac on my processor is fine.

I think the toughest part of all this is that you’ll find that the world
of surround processors is littered with compromises.  For instance, the Classe sigma SSP won’t include a 12V trigger...which might be a deal breaker. The McIntosh MX160 doesn’t have an HDMI 2.0b compliant chipset so you can never get HDR10 or DolbyHDR. The MX122 is literally a Marantz 8802 with some mods. The 8802/Anthem AVM 60s are probably the most solid choices, as in full of features, but the AVM lacks aes digital connectors and the Marantz has an Fm tuner I didn’t care for. The Krell system has a trigger and 2.0b chipset, but doesn’t have a USB port!

it kind of goes on and on. It’s super frustrating. 

Auxinput has a point about the loss of the newer codecs if you bypass the processor to go to the TV. It’s all about compromises, I guess. What can you live with?

One other thing to note: the Krell Foundation does not support HDR. It’s stuck at HDMI 2.0a, not 2.0b. There will be no upgrade to push it to 2.0b. Apparently Krell will release a new, larger system in 12-18 months. 

If you have a new TV with HDR, then I recommend finding a system with 2.0b. The NAD M17 supports that, with the 4k board. 

I think, unless you have a L/C/R speaker setup you like, or want to have, a two speaker amp is enough. To be honest, I was using a L/C/R, with plans to use SL/SR once I moved into my new house, but I recently dropped the C because it was hard to balance the levels with the L/R (didn’t help it was a different brand from the L/R). 

I’m also a believer in minimizing failure modes.  While having lots of separate amps may take up space, if a component on a big, multichannrl amp breaks, you’re in a world of hurt. If one amp in a multi amp setup fails, you can still listen to something. Mono is better than silence.