Sound quality issues streaming from Tidal vs CD


I am hoping someone familiar with streaming from Tidal might be able to help.

I have recently installed the Pro-Ject Streambox S2 Ultra, which is a small Raspberry Pi based network bridge. I connect this to my router via ethernet cable and to my Vitus DAC (which is part of the CD player) via USB. My CD player obviously outputs through the same DAC.

The sound quality from CD is so much better than the sound quality from Tidal (I am a Tidal Hifi subscriber).

So my questions are:

1. Is this just a feature of streaming via the internet, it simply is not as good as a good quality CD transport?
2. Or is it an issue with the Pro-Ject - would something like the Autralic Aries G2 (also a network bridge with no DAC) which costs 6 times the price of the Pro-Ject, improve the Tidal stream?
3. Or is it the fact that the USB cable I am using is an entry-level £10 cable?
4. Or is it Tidal? - would Qobuz sound better?

Any advice or knowledge would be welcome.
128x128duckworp
IMO, it’s important too have a good quality router. I use a Nighthawk connected by an Audioquest Cinnamon ethernet cable direct to my Streamer Dac (Oppo). I’m considering getting a linear power supply for the router based on comments read on Audiogon.
I agree with tuberist above that a high quality router is required for Tidal and Qobuz streaming.   I use the Luxul WIRELESS ROUTER KIT – EPIC 3 AC3100 WIRELESS ROUTER & CONTROLLER W/ DOMOTZ, ROUTER LIMITS AND XAP-1510 AC1900 ACCESS POINT.

"This wireless router kit combines high output power and simple deployment. The Luxul WS-250 offers the Epic 3 dual-band wireless AC3100 gigabit router, and the high-power AC1900 XAP-1510 access point. Including 802.11ac wireless coverage, Domotz remote management, family scheduling with Router Limits and roaming is solved with the built-in wireless controller with Roam Assist™".

https://www.luxul.com/kits/ws-250.aspx
Even though you are paying for hifi through Tidal, double check your settings to ensure you have selected the best sound quality.
I have a PC to DAC over USB and using the DAC’s Window’s driver to drive the USB makes a huge difference, so whatever is driving your source-end USB could be the bottleneck. 
Try looking at the QoS setting in the router. If on turn off.  Otherwise use QoS to prioritize Tidal traffic over other traffic.

To be honest I have no idea how to do it. :)