upgrade question regarding DAC and streamer

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. 

I would consider a Grimm MU2 as a DAC and streamer combo that has spectacular imaging. As a bonus you get a really good analog preamp with line level input. 

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Why would a better preamp improve sound?

@jrdavisphd You are getting some really good advice and everyone has consistent themes.  In my own journey cycling through gear, what I've found through trial and error that aligned with advice dealers and other audiophiles have provided.  Speakers make the biggest difference when you chasing a certain sound, that's followed by the amp / room treatment as the room treatment is basically an extension of the speakers.  Speaker placement is also key.  The Pre Amp is next in line, followed by the source.  Now, this assumes that when you get to the source, you have a decent source, a solid vinyl rig, CD player or streaming set up, they don't have to be world class or crazy expensive.  If you haven't already, I'd try different sources, vinyl or CD, if you get more of the sound you are chasing with those sources, you have proof of concept that the rest of your gear can deliver that sound you are chasing, will confirm that if you tweak your streaming set up you'll be rewarded.  I'd then see if a dealer would let you trial an app, pre separate set up along with a streamer / DAC.  Sounds like a big ask but I've had a dealer provide me those.  You could then experiment, drop the pre into your existing set up, using your Mac as the Amp and DAC, then try using the pre and a separate DAC.  This will allow you to see what makes the most difference with your speakers, room which is already your anchor.  Synergy between your speakers and Amp. are key and then through the rest of the gear.  Think of it like a car, your speakers are your chassis, drivetrain, suspension and the amp is your engine.  If those components aren't paired well together, nothing else will be quite right.  The Pre is like your transmission, if that's not aligned with the engine, chassis, drivetrain the car won't really reach its potential.  In streaming, if you have a solid streamer, you already do, a DAC will have a bigger impact on sound but in your system the streamer / DAC is what would take the rest of your gear from good to very good to great, in your case more likely from very good to great.  The DAC would be like swapping a set of serviceable tires to high performance, if the rest of the car is set up to take advantage of the high performance tires, the change in performance will be noticeable.  If you then switched fuel from 93 octane to racing fuel, if the car is set up to benefit from the change, you'll notice a difference, that's a streamer in this case.  In all this though, if you have the chassis / drivetrain of a truck, a Turbo Charged engine designed for speed but not for torque or towing and a transmission designed for a family sedan, won't really matter what tires or fuel you use, if you have the chassis, drivetrain, transmission all aligned, a decent set of tires and 87 octane will still give you a heck of a thrill, better tires and racing fuel will give you that little extra that takes you from very good to great.