Streaming transport recommendations

Thank you both for your input.

I can second the Melco, I had the N1A/2 and was very impressed.  Now I have the N1Zex

Musicairo,
I've had the Melco in my system for 3 years now.  Had first heard it a year or so earlier at a seminar hosted by my longtime trusted local dealer and was very impressed.  Tight fisted audiophile that I am, purchased my N1A at a considerable discount when the N1A MK2 was announced. I was able to pick up the older model for $1500. It was my first audiophile grade NAS. Prior to that all my uncompressed Flacs were stored on a much more pedestrian $100 WD My Cloud. Used Melco N1A like mine currently go for around $1000 when you can find them. I originally used my N1A just as a NAS with a Bluesound Node hooked up directly to its player port. Only after acquiring the Qutest about a year ago did I begin using the Melco as a music server.  The Qutest replaced a Bryston BDA1 in my main rig.  In November I picked up a Roon Nucleus, and now have the Nucleus hooked up to the Melco's player port, with the Nucleus hooked to the Qutest via USB.  Here is my system as of October:  https://systems.audiogon.com/systems/8156

As to your question:  HDD vs SSD.  From what I've read I think the real gain as you step up the Melco line is not so much going from HDD vs SSD but in increasingly better treatment of both the power supplies and damping of the storage mechanisms.  Everything is about reducing noise, both electrical and mechanical and dropping the noise floor. It's all about how much you are willing (and able) to spend.  And like most things in audio, a law of diminishing returns inevitably sets in. As good as the N1A is, if you are willing to spend there are models that are even better. 

Thank you Jazzman7! I'll have a look at those.

The Melco offerings seem to double in price if you choose SSD (haven't checked Innous yet). Is the difference justifiable in you experience? 

In your shoes I'd be looking at the Melco and Innuos offerings.
I own a Melco N1A.  I've used it with a Chord Qutest via Curious USB cable.  Superb results streaming from my own personal library of uncompressed Flacs, that is where the Melco shines;  can also use it to stream from likes of Tidal or Qobuz, but there I prefer convenience of Blu OS or Roon interfaces.   Melco has both newer and more advanced models in their lineup.  Melco and Innuos take a similar approach to their ethernet connections, in that they both feature both a LAN Port and a Player Ports (think of it as a 1 port ethernet switch, and act as an ethernet line conditioner).