esthlos13,
To me, hiss, hum, buzz, anything that detracts during quiet passages destroys a black backdrop. What i was mentioning is that for an amplifier that really is well designed, tube units seem to have less in the background during quiet passages. This is for units that are basically quiet quiet quiet.
If a unit is not quiet to start with, there is no black background. When it's right you get the notes splashed in color across a wide canvas. There's nothing to distract you except noise in the street and perhaps the refrigerator doing what it does. Generally, unless it's quiet in your room already, say that you're listening at night, you won't notice what I'm talking about at all.
If it's dark and quiet though, and there is a diminuendo followed by silence, you want silence. That's the whole idea. At those times, if there's noise of any sort, including a silk instead of a velvet backdrop, you notice.
Those times at night are when you really hear, not when you're blasting the dance music out. Honestly, most of the time it's just not something you even think about.
Tonight, when it's quiet and there is no traffic going by and the cat's asleep,
see if you can feel the system being on or not. Most times, you can.It's great when you have to look at the indicator lights to tell.
That's a black backdrop.