Very good AES presentation on inter connects and ground loops.

There is  much more to. It then that ,myself and many others in our audio club some are true electrical engineers. ,for. Example digital noise can  travel house to house that is why I isolate the coaxial filter, plus the Ethernet the Ethernet hub I use has low noise regulators ,linear-power supply,as well. As A  OCXOover controlled precision clock feeding the Ethernet cable , and put in a upto date Modem router combo ,I bought the Motorola 8702 which has docsis 3.1 which is much faster, bigger buffer , even the wifi for the tv is better , and having a Quality LPS power supply to the router a 12v 4+ amp is night and day better sounding then the garbage wall warts that come with the router ,I have -0 wall warts in my system 

and quality Ethernet cables over $4500 the 2 Ethernet, and usb cables Ethernet switch and LPS , efore the dac and streamer .if you want great digital performance 

to surpass turntables youhave to spend $$ with the same precision you give to any

high quality turntable arm and stylus leave no weak link in the chain  ,

and with XLR if all components  are truly balanced for each item then sonically  it’s much more quiet. Transformer coupled. This too cost $$ to do it corrrectly.

Folks, because something CAN, does not mean it DOES.  Listen to your system yourself and see if you have any of these problems only copious amounts of money will solve.  With my preamp turned all the way up, I hear dead silence right next to my speakers.  

Totally false assumption all wall warts are the same. For instance, JDS uses AC transformers only. 

XLR transformers do in fact have higher CMRR as they are truly balanced if that is your problem. Great for 100 foot runs. They also have higher distortion.  My DAC to preamp cables are less than 6 inches.  I don't have a problem. 

I too am an engineer. I learned to solve problems that do exist, not because they can exist.  So, have you re-wired your house with hot and neutral twisted, separate ground, pulled into thinwall?  Do you use only commercial grade outlets? 

I have an AES input on my Schiit Modius AKM4493 dac. I’ve been tempted to purchase a transport with an AES output to use with the Modius, such as the Shandling ET3. As for using computers for streaming music, I have been using Amazon Fire tablets for the past few years, with outboard D to A converters, with excellent results. IME, sound quality seems to be more dependent on the quality of the digital sources than anything else. Many sound unimpressive. However, the better quality higher resolution source material can sound quite exceptional.

Are we blaming the wrong part of our systems?  Are we blaming the environment, not the manufactures who fail to properly design something to work in it? 

If you buy a $80 CH-FI wonder, the FOSI V3 for instance, we expect every corner to be cut. With a background in manufacturing, I am truly amazed.  OK, It will come with the cheapest power supply they can buy. If a cheap DAC, sure, an almost shielded fifty cent USB cable. Do my Elac 5.2's have cheap binding posts? Sure.  What excuse is there for boutique priced equipment? 

Domestic power is well understood. Cable/Internet is well understood. Ambient RF is well understood.  If you make a product to work in this well understood environment, why should you be asking your customers to go buy external band-aids?  You buy a $5000 DAC and then expect you have to add an external clock? External power supply? Magic cable? ( as the $2 one works perfectly).  BLAME the maker of that high priced garbage that did not design their box to work in the environment it was sold into!   OK, I build an amp on an old Hafler chassis. 2 wire cord and it is not double insulated.   Even I can put a ground isolation circuit to retrofit an old chassis with a 2 wire power cord to a proper safety ground.    Problem solved where is should be, not with some magic external box.  Sure, PC's are noisy dirt cheap with every corner cut.  USB is pretty rough.  Granted, an Apple Dongle for $12 won't have much in the way of filtering ( though not bad either), but there is then no excuse once you cross the $100 or so level to not have a decent USB receiver, galvanic isolation and good PPL. ( Schiit USB is very good) No excuse for the DAC to rely on the sloppy computer clock to feed the DAC. We did invent buffers you know.  My $99 Atom can and it is not even leveraging off-shore slave labor to make. 

So, why do we think because something is used in a studio we need it at home?  Because marketing has said we need a AES interphase, we need XLR to go 2 feet, we need 192/36 DAC to play Redbook?   We need monitors designed to highlight flaws? ( Think L100's) 

Caveat: If you play physical CDs and so are real time streaming, then I would expect a modern transport to do a better job than say, my old OPPO. I only play FLAC off my SSD, so any timing and buffering is taken care of.  Problem solved without high dollar boutique solutions. And I can drag several CDs to the que and walk away not getting up to change them. :)

Yes, headphones can have a much lower background level and if you keep the volume down, quite impressive details are discernable even from a CD. No crossovers to screw things up.  I hate headphones, so how much better the hi-def (compared to what?) streaming may be I don't know, but I have heard demo's on very high end speaker systems ( like Wilsons) in stores and heard zero difference.  So 24 bits for a source that was maybe 12 bits to start with.  Not impressed.  Differences in DAC design? Clear and dramatically different. 

I do know a little about sneaky problems.  Did you know a 9-track tape drive sees about 60pF to a raised floor in a computer room?  Deal with that RF loop!  How about IBM requires third party to be on a different entrance panel. Want to measure RF on ground? How about THOUSANDS of amps!   We fixed these problems by proper design of our equipment, not external hacks. 

@audioman58 you have certainly wasted a lot of money on things that cannot have an impact, to OPs point.