More information would be really useful. It would really help us to see your system, if you create a virtual system and photos.
Given what you have asked. The real question is where do you want to go sound wise?
Right now your MacIntosh is probably supplying some warmth that an all Moon system will not have.
Really the most important thing is to identify the "sound" you are going for. On one end of the spectrum is highly detailed, lean, somewhat analytical systems with good slam. On this side is also what I call "sonic spectacular... crazy holographic imaging". On the other end is highly musical, natural sounding with great imaging, midrange bloom, great rhythm and pace. Combining different house sounds can make a perplexing number of different sound types. Moon is pretty detailed and a bit on the analytical side. MacIntosh is a bit on the romantic musical side... but lacking in detail. Your current combination may be pretty good. Focal tend to be hot on the top... so you Mac will help calm that down.
I am not a fan of combined streamer / DAC / Preamp systems. They are too much compromise... depending on your expectation. Note for instance, what is probably the best stream on the market is the Aurender N50 a three box solution, a great preamp is the two box Audio Research Ref 10. You get the idea... great sounding components are single function.
I would recommend a Aurrender streamer... N20 or better. And a good DAC... in the $ 7 - 10K range. I would love to recommend the Audio Research Ref 9... but it is getting long in the tooth. Berkeley Alpha is a great DAC. The DAC can be a critical decision because, like a preamp, it can influence the tonal balance... detail / musicality. It is easy
Before I could recommend a preamp. I would need to know more about your tastes. It is the key... and I think you need to be very careful.