There are so many ways to do things but I am able to give you some feedback.
My system is based on a dac/pre/amps and speakers that would have been about 12,000 Euros when new, to give some background.
I use a 6 year old NAS and WiFi and for years used a Mac Mini with Audirvana. I then bought an Allo Digione, Sonore Microrendu and an Auralic Aries (Femto) and compared the 4 alternatives.
My Mac Mini is not modified for optimal performance and whilst not bad I would suggest that the latest "streamers" are better value for money and easier to use.
The Allo Digione (similar to Raspberry) is absolutely fantastic value for money, but unfortunately it was not as good as the Microrendu which was not as good as the Aries. I am now just using the Aries.
(I do note that the 3 streamers I am writing about have been superceded by better/more expensive alternatives.)
What I like about the Auralic products is that they recommend WiFi - which takes alot of other issues/expenses out fo the equation.
I do believe that with your system you will easily be able to hear the differences and I would suggest that you should look at the top of the range products offered if you look at Sonore/SOtM/Aries.
To cover your question re Server/NAS/RipNAS etc.: When we look at a DAC the underlying premise is that the music is stored somewhere in digital format. So where is the music? On a CD/BluRay/Hard Disk/NAS/Tidal, Qubuz, other ? The various solutions being offered are either "ripping" from a physical disk to a hard disk or buying/downloading music to a hard disk or just streaming via the internet. You need to decide how you get your music and where it is stored.
If one uses a NAS you need a computer and disk drive to rip and or downlaod the music and save on the NAS. MAny of the servers being offered do that and hence removes the need for the computer etc. In other words it may not be that expensive to go down that path.
A typical NAS is designed for normal data storage etc. and not for Audiophile music. The dedicated servers are designed for music only and for example has better power supplies and produces less noise.
I have not personally reviewed/compared all these music servers, but from reviews it appears that the sound quality is better. I believe you have to listen for yourself.
In summary, for music stored in electronic format the first question is whether you would like to play back the music via computers and software or via a streamer. Once you have decided which route you are on you can look at your options. It appears the new Mola -Mola dac will have an ethernet port. That means it will become a streamer as well. If you go down that route the next question is then: do I store my music on a NAS or on a more expensive music server.
All the best.