Why are digital streaming equipment manufacturers refusing to answer me?

I have performed double blind tests with the most highly regarded brands of streamers and some hifi switches. None have made any difference to my system on files saved locally. I have asked the following question to the makers of such systems and almost all have responded with marketing nonsense. 
My system uses fiber optic cables. These go all the way to the dac (MSB). Thus no emi or rfi is arriving at the dac. On top of this, MSB allows me to check if I receive bit perfection files or not. I do. 
So I claim that: if your dac receives a bit perfect signal and it is connected via fiber optic, anything prior to the conversion to fiber optic (streamers, switches, their power supplies, cables etc) make absolutely no difference. Your signal can’t be improved by any of these expensive pieces of equipment. 
If anyone can help explain why this is incorrect I would greatly appreciate it. Dac makers mostly agree, makers of streamers have told me scientific things such as “our other customers can hear the difference” (after extensive double blind testing has resulted to no difference being perceived) and my favorite “bit perfect doesn’t exist, when you hear our equipment tou forget about electronics and love the music”!
One designer of streamers confirmed that his effort is to reduce any emissions via air, cable and power. My “strawman” above addressed cable. I don’t know about air especially since fiber allows us to move the streamers or NUC as much as a kilometer away! About power however I get the point. That could have an effect. The way I may have indirectly dealt with it is that I run the custom nuc with a linear power supply (150$ from China!) and I always isolate my front end (other than the nuc) with isoclean or balanced transformers. M. 
One of my good friends recently became an audiophile and has finally agreed that the most important variable is actually what you hear not what science tries to prove. 
HI yyzsantabarbara

Both Qobuz and Tidal use the Rest API for streaming. The following is a generic example of a streaming session using Qobuz/Tidal; Audirvana and a streamer/DAC using UPnP/DLNA.
Audirvana will issue a REST request over HTTP to the Qobuz/Tidal server. Your computer will create an TCP/IP connection to the Qobuz/Tidal server and transfer the request after the connection is established. Your computer will also use Ethernet to transfer the HTTP, TCP and IP protocol data units to your router for transmission over the internet. The Qobuz/Tidal server will respond to the REST/HTTP request over the TCP/IP connection. Once the response is complete the TCP/IP connection will be closed.
TCP/IP will provide error free sequenced packet delivery between Audirvana and the Qobuz/Tidal server. If any packets are lost it will automatically re-transmit them. Ethernet will provide error free frame delivery between your computer and a switch/router.
Audirvana uses the UPnP protocol suite to transfer the media content received from Qobuz/Tidal server to your streamer/DAC. It will use HTTP, TCP/IP, UDP,  Ethernet and other protocols.

You will get error free delivery from Qobuz/Tidal to your streamer. There can be reduced band width on your connection due to network congestion/errors.
Pased on the elegant prose in your opening statement, I have no idea.  It's not as you sound like a rambling nut case or anything.
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