“Black background” — What really contributes to this phenomenon?

I’ve found you have to filter EMI/RFI from as  many physical connections into your system as you can to achieve the true experience of the recording. Mains supply is obvious and for those who stream from subscription services or locally stored FLAC, the Ethernet cable is another delivery system for it. Filter out RFI from your Ethernet for happy days.

Miller's whining on about springs again.   Boing boing.
Just the wrong way to go.  Equipment shouldn't be allowed to oscillate.
Particularly speakers, springs lead to fuzzy unfocussed sound. Blowing in the wind.
Even TT designers have mostly moved from spring suspension to mass loading in the last 10-15 years.
And the more mass the better.

Interesting points but you could save time & effort by purchasing a Puritan PSM156. I did. Incredible. 
Don't listen to pricks who haven't tried one commenting on filters. It works perfectly. 

In my experience, a black acoustic background is elusive for all the reasons cited by previous commenters. I have a few years of experience with sound reinforcement as well as an audiophile. From that perspective, I may be able to offer a few practical solutions that can isolate your audio from electrical noise that can creep into any system, no matter how well designed each component.

1. Start with audio components and signal cables that are well shielded against RFI and EMI. I've found that XLR cables resist RFI and EMI as well as premium RCA cables. If you use components that accept XLR plugs, you may find that their greater cost is offset by the relatively lower cost of good quality XLR cables, i.e. Canare. In fact their solder connections are easy enough to use that most persons can customize their cables with a minimum of fuss.

2. Star ground your components to a single and EFFECTIVE grounding point. Any component whose mains plug doesn't include a grounding pin or uses a grounding pin lifter defeats the purpose. I prefer removable IEC plugs because I too often find that the component's cable receptical has no grounding pin. Unless you take this step, your system is susceptible to ground loops which introduce hum into your audio signal.

3.  If you can, use a single 110 V. outlet for every component in your system. Homes that have 220 V. electrical service use two of the three "legs" furnished by your electrical utility service. If you can't plug everything into a single outlet, ensure that every outlet you use is on the same "leg". If you skip this step, your system will be susceptible to hum.

4. Plug all your components into an effective power conditioner that can handle the total power your system requires. IIRC, Monster offers three levels of power conditioning to consumers. I use their most comprehensive conditioner in my system. This not only protects your equipment from power spikes, it also isolates the system from electrical noise induced from outside your system.

5. Above all, trust your ears.

My most recent experience in this arena was eight years ago; and the suggestions I've offered could be obviated by ongoing advances in technology. Also, please understand that the list of solutions I've offered may not be exhaustive.

Happy listening!

A thought on Noise (the nemesis of silence between notes) starts at the front of the gain stage chain (assuming that all the stages are working right).  It has a simple equation from information theory,

 Noise = f + 1/f  + 1/f^2 + 1/f^3 . . . .

So look to the beginning of the chain.

Resolution in audio focuses on the distortion of the timbre of the sounds to which you are listening.  Noise between the notes is the biggest problem, as I have written elsewhere, it is a cascading effect, most pernicious in its nature, one hard to combat, and completely disruptive of the illusion of reproduced music.