upgrade question regarding DAC and streamer

I agree with others in this thread that stated this is a complex question and that sound quality, especially staging, imaging, and timbre (most important to me) is affected by system component synergy more so than an individual component.  To me, upgrading a system is a process.  I will outline the process I use.  

1. Establish your perception of the sound of live, acoustic musical performances, both large venue orchestral compositions and small venue chamber music, ensemble jazz, and rock).  Large venue rock and jazz is not a good benchmark due to the engineering challenges faced in large venues and variability in sound quality at different seating positions.  Note instrument timbre, imaging, image density, staging, macro and micro dynamics, and how the sound blooms from leading edge to harmonic decay.  
2. Listen to well recorded music, comparing your perception of how live acoustic music sounds and noting differences you which to focus on for improvements.   
3. Research trade journals for equipment in you budget where the author publishes the equipment excels in sound quality attribute you have identified as an opportunity for improvement. 
4. Find a good dealer that will let you do an in-store head to head evaluation or better, an in home evaluation, and with a good return policy (with or without a restocking fee.  Validate the published review and determine if there is a high benefit/cost ratio.  

Responding directly to your question, changing your digital front end can make an improvement in staging and imaging, but you need to be more specific in defining the improvement you wish to make.  The attributes of staging include, without limitation; width, depth, presentation (forward or back stage) image focus, image size, image density, ambient bloom in the spaces between performers, ambient bloom into the venue.  I will give you my impressions of some DACs you are considering.  Remember, my impressions are based on my perception and my ears, so it is a subjective opinion.  Your current Innuos DAC has exceptional staging and width, and good focus at its price point.  Is presents a more backstage presentation  that is light in density and airy.  The DCS Lina will be an improvement in all sound quality attributes but will still be a further back presentation, light in density and airy.  It will reproduce excellent between instrument and hall ambience and harmonic decay.  The MSB is my favorite of the three that will have a up front presentation with dense and palpable images, as well as the between instrument and hall ambience.  Others to consider include the Mola Mola Tambaqui, which to my ears is the timbre, dynamics, and soundstage champ, except for between instrument ambience retrieval where the DCS and MSB are better.  The MM has an up front presentation (not to the liking of some but to my preference) with excellent width, depth, and focus.  The ARC DAC9 excels at bloom (best of the bunch), ambient information retrieval, palpable image density, and stage width and depth.  Each of these exceptional products have a distinctive sound pallet, so you need to read information on them and audition to determine which you like.  The Nagra is pricy but also an exceptional DAC for the same reasons noted for the ARC.  
 

Improving your amplification will also help.  Others have mentioned ARC and CJ tube designs, and Burmester (which I personally do not find dry but rather sweet and highly musical).  Others to consider Audio Note (my favorite but above my means) and Gamut.  All have their own sound pallet so in repeating myself, research, audition, and choose what brings you emotionally closer to the musical composition and performance.  The only right or wrong is determined by your own ears.  Good luck.  

@jrdavisphd     I think others have given good advice--your streamer is not likely to be the problem. 

I would want to know what you're seeking when you say "imaging."  More pinpoint focus, perhaps?  I don't think real, live music sounds like that, but some audiophiles want that anyway.  Are the images your system produces larger or smaller than the real instruments?  Answers to those questions might yield more useful directions.

I think speakers and the room contribute a lot to imaging.  I'm not familiar with your speakers.  If your room is too reflective or asymmetrical, that can screw up imaging and require room treatments or different speakers for improvement.

OP

 As one of the posters had posted the Pre-amp seems to play a significant Role.

you have done quite well for the room treatment and that is the most important part for the imaging you are going for. The dcs Lina and streamer combo is very good

You will hear the changes distinctively. 

Your speaker is top notch and so is your amp. if you think/hear your speaker amp combo is working with good synergy, then an external pre-amp may help improve it. OR you may then spring for a complete separate. Then at that time, I would recommend the gryphon family. I heard it in separate occasions, and I have to say, it is a level of its own

good luck

Very thoughtful and well posed question.  Very nice system--the system detail in your ask really helps.  Myself and all my friends in the hobby with systems at this level are all using separate DACs and streamers.  I would advise the same and not get a combo unit. 

Your DAC is a weak link so I would start there.  Get the best DAC you can and use the onboard clock.  The improved clocking will greatly enhance your imaging. The next step would be to upgrade your streamer which will improve the imaging further.  Good luck and cheers.  

I have a Macintosh MA 8950 paired with Dynaudio Heritage Special speakers. I owned a BlueSound Node 2i streaming Tidal into the Mac DAC, the DA2 module. After a few years, I was looking to upgrade in search of better sound, decided the weak link was my streamer so I bought the Innuos Pulse, retails around 3200. When I added that piece, I didn’t hear an immediate improvement instead I thought things sounded less integrated (for lack of a better way to describe it). I then auditioned the Aurender N200 and liked it very much but wasn’t prepared to spend $6000 for it.  Also, some research told me that the DA2 module DAC in the Macintosh might now be the “weak link’”. I started auditioning external DACs, the Lab12 and the SPL, average between the two is about 3k.  Each of these DACs made it clear that better sound stage, separation, depth, nuance could be obtained through a different DAC. Then my dealer got the Hegel D50 DAC into the store (4,900). I took that home, auditioned it and found it to be better than the other two DACs that I had tried.  I bought that DAC.  My system sounds great.  What I said to my dealer after this process is….You don’t know what you don’t know until you know it. That is the revelation that I had improving these pieces in my system.  I always thought the Macintosh/BlueSound sounded great and was skeptical that I could improve it at all but knowing my streamer was $600, I thought spending more money would make an improvement. So in the end, $8k later, my system sounds great.  I hope this helps in some way, just from someone who owns the same McIntosh amplifier.