[1] I can reliably hear the differences between 24/44, 24/96, and 24/192. Not to mention DSD Files. Dynamics, and noise are pretty consistently what stands out between all these files, less noise on higher quality files, better dynamic range.
[2] DSDs sound more analogue, [2a] "like I am there" than any other format.
[3] If I was you, I would get my ears checked, or invest in better gear.
1. There is no dynamic or noise differences between any of those formats, they are all have identical dynamic range and noise, except DSD which has significantly less dynamic range than any of the others. So how can you reliably hear differences which do not exist?
2. That's a bit of a sad indictment, do you really think DSD sounds as bad as analogue?
2a. I don't understand, if you think analogue sounds "like I am there", why do you think they invented digital audio instead of just sticking with vinyl or cassette tapes?
3. You're the one "reliably hearing" differences that do not exist, so shouldn't it be you getting your "ears checked"?
One misconception though is that the CD is DDD. It is actually DAD as it was mixed through an analog work station.
The CD codes were rather misleading. DDD doesn't mean an album was mixed digitally, the 3 letters ALL refer to the recording of the 3 stages: The first D indicates the audio was recording in digital, the second D indicates the mix was recorded in digital and the third D indicates the master was recorded in digital. So, you can mix and master with an analogue desk/equipment and it's still DDD (rather than DAA) providing you record the analogue mix and master in digital and indeed, this is the case with pretty much all DDD rock/popular music genres up until the millennium.
[1] Thank you for that history, but my question remains: When did higher sample rates and bit depths start to be used in production?
[2] When you record something in digital, then apply processes(EQ, comp, etc) digitally to it,
[2a] it's like a recording of a recording of a recording, and quantization noise and other artifacts slowly accumulate.
[3] That is why 24bit and higher bit depths, and 92kHz and higher sample rates are used in the production process before exporting down to 16/44.1 for consumer mass-distribution.
1. 32kHz, 44.1kHz and 48kHz were the standard for many years, 96kHz started to be widely available to studios in the early 2000s. 20bit recording started to be employed in the early 1990s and 24bit again in the early millennium.
2. You're confusing "recording something in digital" and mixing ("applying processes") in digital. At the beginning of the 1990's (and even a few years earlier) there were digital mixers that processed internally at around 28bits but they weren't particularly common. By the late 1990's professional digital and virtual mixers were 32bit float or 48bit fixed, today they're mostly 64bit float.
2a. Not really. There are no other artefacts besides quantisation noise and that's defined by the bit depth of the mix environment. So with 48bit fixed, the quantisation noise is roughly at -288dB and around -370dB with 64bit float. You literally need hundreds or thousands of processors for quantisation noise to accumulate to anywhere near audible levels. This is independent of the recording bit depth, these quantisation noise figures are the same regardless of whether the recorded audio being mixed is 24bit or 16bit.
3. There are and have never been any 24bit professional mixers as far as I'm aware. Sampling rates are a bit more complicated; 48kHz is by far the most common sampling rate used professionally/commercially, as it's the worldwide standard for film and all SD and HD television. There are few situations where a higher sample rate is beneficial when processing but this is again independent of the recorded audio sample rate and even independent of the sample rate of the mix environment, the processor will internally upsample and downsample if necessary. The only legitimate use for recording at 96kHz or higher sample rates is for some sound effects design purposes and for scientific purposes (recording insects or bats for example). However, 96kHz and 192kHz are reasonably common as recording formats for music products because clients may want to market a "hi-res" version at some stage.
G