The hiss or the scratchy noise one hears from music played back in the vinyl format has been cleaned out by the digital recording process, such that what one hears from CDs are pure sound signals, nothing more, nothing less.
For over two decades since the CD was introduced, engineers have gone through a tedious recording process digitizing an analog signal to produce a CD only to convert it again to analog during playback. The funny thing is that they go to great lengths to emulate analog sounds only to subject them to filtering, noise shaping, data compression, etc.
And since the CD has a limited storage capacity, frequencies lower than 20 hertz and higher than 20 kilohertz have to be eliminated, with the argument that those frequencies are way below and above humans’ hearing range.
All the sounds we hear around us  the wind, chirping of the birds, raindrops falling on our roof, our voices  are analog. Thus, reproduced sounds must be in analog form for us to hear them. What digital recording does is to convert analog sounds into numbers (one and zero), so that they can later be electronically stored, manipulated and distributed.
The process is very much like taking a picture of the analog sound. For a CD recording, engineers take 44,100 pictures of sound per second (sampling rate). The pictures are then converted into data with an accuracy of 16 bits (each of these 44,100 pictures must be transformed into one of the 65,536 [2^16] possible values).
This is why vinyl is still superior to CD when it comes to recording and playing back sound. Think of a CD recording as a huge cabinet with many drawers. Some sound information would be lost since the pictures taken have to be limited to the maximum that is 44,100 per second. And to think that each of these pictures must fit in one of the 65,536 drawers of the cabinet.
In contrast, vinyl records are pure analog. The grooves engraved in it are the exact replica of the original sound wave. The analog sound signal is then amplified to produce music. In this process, there is no picture taken, no sound conversion, and there is definitely a limitless number of pictures and likely values.
To recreate analog sound, the Nyquist Theorem says the sample rate must be at least twice the highest desired frequency. Therefore, to devotedly reproduce a bandwidth extending up to 20 kHz (the upper range of human hearing), the sample rate must be at least 40 kHz (2 x 20 kHz). Thus, the standard audio CD sample rate was fixed at 44.1 kHz. But even at this rate, CDs couldn’t possibly store all sound information needed to reproduce analog sound waves.
Debates rage on whether there is a need for higher sample rates and higher resolution to "store" analog sound faithfully. Some say 44.1 kHz is sufficient since the only cut-offs occur at frequencies higher than 20 kHz, way above the range of human hearing. Others see the 16-bit word as more than enough resolution for precise sound reproduction. Nevertheless, because all frequencies intermingle acoustically to construct a waveform, it is only fair to believe that capturing a broader frequency range and having a more accurate resolution are necessary.
CDs do reproduce squeaky clean sound, but it is a reproduction that is so wanting of the warmth and glow of the music played back on vinyl. When you pluck a guitar, for instance, the CD will accurately reproduce the notes made by the guitar strings. The vinyl will do more than that: it will capture and give the added harmonics of the notes that were struck or the "halo" effect that is so evident when one listens to music reproduced on vinyl. If cared for properly, vinyl can be smoother and quieter than the CD. With vinyl, nothing will be lost in translation.