Should I get the Moon 891 streamer/dac/preamp for my Moon 861 amp? Or separates?

Moon 891 doesn’t use newer technology than Chord DAVE. It uses different technology. 
Moon uses off the shelf chips in their DACs while Chord DACs are FPGA. 
What is 891 primarily? Is it a DAC with streamer and preamplifier sections? Or is it a preamplifier with a built in DAC and streamer sections? You have to know the answer to this question. Call SimAudio. 
 

If you keep your McIntosh preamp adding Lumin/DAVE combo could actually give you good results. Using DAVE’s preamp section could be OK but I suspect it might be too direct sounding with 891 and Focals. Try it. 

I have the Moon 891/861 combination and it is amazing. Very clear, musical, dynamic sound, and excellent bass and soundstage. I use th Moon 810LP phono preamp not the one built into the 891 (and have not tried it). There are three options on the streamer that I use: run Room Nucleus into the 891 DAC via USB cable; use Roon as a controller for the MIND streamer as an endpoint; or use the MIND software to control MIND. The Roon directly inputted to the DAC via USB or the all MIND options sound totally amazing and cannot imagine wanting better sound. I don’t think Roon as a controller for MIND is as good as the other two options. Buying separates would not be worth it unless you want to spend far more. According to reviews and Moon, the preamp in the 891 is the best that Moon has offered at any price and hard to beat relative to other options under $35,000. The built in case phono preamp has very good reviews as does MIND.  I am completely happy other my system which has AudioQuest Thunderbird interconnects and speaker cables and Diamond USB, Niagara 5000 power supply, GoldenEar Triton Reference speakers; and a Rega Planar 10 turntable with Aphetta 3.  You would need to get into a whole higher price point to improve your sound over the 891/861. I have no points of dissatisfaction with my sound, plus you get an amazing remote control with the 891 that is a very high quality dial and display (and very cool).

Hello @dman777 ,  you have a wonderful amp.  Like some, I am in the separates camp and realize the benefit of that more now than ever.  I also believe a quality preamp is almost always better than a volume control in a DAC or DAC / streamer.  While I have Audionet amp and preamp in my main system, I have a Moon integrated in a vacation home and love it.  My case in point about separates is that I have changed my DAC and my streamer, but keep my amps and preamp.

i would consider keeping the Mcintosh for now and trying a quality DAC.  That way you are using the same volume control and know the pre amp sound.  And this from a decidedly non McIntosh fan.  A used Tambaqui can be had now for under $8,0000.  I am sure the digital volume control on this great DAC is not as good as your present preamp.  But  am also sure the DAC is world class.

i don’t think you can easily perceive what a good streamer brings until you have a good DAC.  That was my experience, and adding a quality streamer to my Tambaqui was another big improvement.

Another way to word your question is ‘how much better is the comparable Moon preamp to their combo pre / streamer / DAC (preamp and volume section)?’

I am sure the answer is better, by how much that is the value / importance question. 

But with separates you will always be able to upgrade (and you will) and will never regret your purchase.

@fastfreight thanks! I am enjoying the sound of the moon amp, especially now that it's somewhat broken in. The only issue is that Moon doesn't really offer a preamp for this tier without a streamer and dac. So, if I want to go with a separate streamer and dac then then I'm pretty much stuck buying a different brand preamp. It wouldn't make sense financially to buy the moon 891 just for a preamp. It kind of bothers me because I would like that synergy I would get with a moon preamp. But as of right now I feel like I want separates for streamer and dac

Having owned Moon in the past, I would want a DAC and preamp that is warmer and more musical than Moon tends to be. So, perhaps this is good.