Next Best Upgrade for Tidal MQA?

1- Good Tube Preamp definitely. It will be significant upgrade in SQ. Modwright LS-100, Modwright LS-36.5, BAT, or Cary Audio could be in your price range. 2 - Node 2i is entry level streamer. You could upgrade it with some thing like Lumin U1 Mini which is transport streamer so you could use it with your existing DAC or maybe Lumin D2, Teac NT-505 with MQA DAC on board will be upgrade to.  3 - If used staff acceptable you could upgrade both options. It not go with new tube preamp. 

You could improve the sound from your Node2i by fitting a Network Acoustics ENO Ag/Cu network filter.

Hey vinyl-guy and OP, sorry I'm just starting to post here that the callout function doesn't seem to be working in Edge.

To OP, I think the difficulty here is you've got a complex stack, you seem to like the sound of it and you're wanting to get "more" out of streamed, hi-res files, so targeting that specifically.  We could go down a rabbit hole if we say "let's spend a few grand," haha, and I'm sure you've been there.  This year, I've made some pretty drastic changes in my setup...the importance of some factors were not communicated to me well (or I didn't pick up on it) but was open to try new things.  I'm not really sold on MQA, and honestly, I've found that straight redbook is fine if it's handled by a superlative DAC.  I run an MScaler and a TT2, and I like being able to use the TT2 as a preamp.  I have also run the MScaler via optical into a Devialet Expert Pro.  Seems bizarre, right?  Well, I found that, between the minor upscaling and the WTA process, it would be a combination I would suggest...the handling of the transients, I've had guests comment that it seems as if they're hearing tracks they love as they were meant to be for the first time.  I have never used it with the Mytek. 

I don't have a background in this, but think of it this way: when we're listening to digital music, regardless of the resolution, there is some element of estimation that is happening to convert that signal from the digital domain to analog.  Filters, different processes, and so on.  The MScaler sneaks up on you, whether paired with a Chord DAC or other DAC.  Depending on the recording, the way in which it works with incoming signal results in estimations that generate a much more believable output.  This is not me trying to say "other DACs are trash" but I cannot imagine putting together a system without it now. While it doesn't do the MQA thing, I don't think it will matter to you if it works well in your system. 

Vinyl, I let Roon do an unfold but I don't really seek out MQA support as factor when choosing a DAC because it would mean giving up the MScaler for a final unfold, which I feel is far less valuable.  I think a false assumption made about the MScaler is that you need to be running it at 705/768 and that confers the benefit.  That's possibly the least-important element.  It's the management of transients.  

Full disclosure, I don't want to really list the whole chain but I have an optimized digital transport I built to stream with Roon, and right now I'm running a pair of Focal powered monitors (40th aniv) from the balanced outputs on the back of the TT2/MScaler stack.  Clean power all around.  Vovox XLRs but considering trying something else.  Is it a little hyper-analytical?  Yes and I love it, because it's quite euphonic as well.  Off-axis isn't great.  But I'm shocked at this little setup and what I'm hearing. And a lot of what I'm hearing confirms the benefits I seem to hear with the use of the MScaler elsewhere. 

Does anyone in US mod the bluesound... High fidelity in UK do new PSU and board... I feed this into chord qutest DAC and then into luxman.... So good I sold my Linn Klimax Dsm and pocketed the change.... Not often I get to do that 

I had an Onkyo AV pre that I replaced with the Parasound JC2BP. I think it made a huge difference in opening up the music for me. I'm guessing you are looking at the JC2BP not just for the sound quality but also for the bypass feature so you can still use the Marantz for surround. Since I got the Curl pre I don't listen to the surround system any more. I also switched from VTL tube amps to a used pair of the JC1 monos. That was a nice upgrade also but it didn't make as much of a difference as the pre did.