I'd second the advice from most here to select (much) cheaper cables and a cheaper turntable.
WiiM Ultra already has a built-in phono input so I'd drop the separate phono box completely. WiiM products also implement both Room EQ, bass management and even a manual 10-band PEQ - I don't believe you would necessarily get any better results with miniDSP.
Loudspeaker placement near the wall behind them is not an issue (actually it is usually even preferable in such small rooms - see
this article by Genelec).
Regarding speakers - for such a small room and short listening distance, I believe ~5" woofers should be perfectly fine - assuming you don't plan to blast it to very high listening levels. Even 4" woofers might work, depending on how loud you listen and whether or not you have a sub.
Here's my view on woofer size, which I guess some will see as controversial: going up for a 7" or 8" woofer on the loudspeakers won't provide as much additional bass extension as you may think, and IMHO doesn't ever truly replace a subwoofer. In this case a bigger speaker mainly means it can play louder without noticeable distortion.
So you'd need to know how loud you want to listen (and how far away you want to sit) to make an informed decision if you need a bigger speaker or not. E.g. Neumann and Genelec both have official guides on speaker size selection which are based on listening distance and required SPL.
To illustrate, here's an example of Neumann KH 120 II vs KH 150 (
source) - you can see that with the larger woofer you'd get only 5-6Hz lower extension:
View attachment 391816
A subwoofer on the other hand should gives you an extra octave below, and it can also be used to offload the bass from the loudspeakers, smooth out the upper bass response and in some cases even to combat SBIR effects (
I wrote about this a little before).
Here's how adding a tiny sub helped me greatly reduce audible bass-suckout in my desktop system.
With multiple subwoofers (optimized with measurement and DSP) you can even achieve a consistent bass response across a wider listening area - though this is not necessary if you have only one listening position.
All of the above can go a long way towards taming the undesirable room effects on the bass, which has a significant influence on sound quality.
However, properly integrating a subwoofer for the first time is not trivial (there's a learning curve to it), and could lead to less-than-desirable results if done poorly. But it is important to understand that it is possible to do it well, and your room size would not necessarily be an issue.
If you want to have room correction and a well integrated subwoofer, how much you need to spend will also depend on how automated you want this process to be.
You could get away with a cheaper system, but then you need to learn more about in-room response measurement, manual room EQ and subwoofer integration as you will be doing all of that manually.
For a higher price you could get slightly more automation and ease of use (e.g. have a look at Genelec GLM and Neumann MA 1 solutions), but that would probably break the budget, and especially if you also need an additional streaming box and a turntable.
All that being said, for simplicity (and to avoid being overloaded with new information), it may indeed make sense to start without a sub, learn to measure and do room correction, and add a sub later.
Hope you'll find some of the information interesting and useful. Good luck and have fun!