Tier 0: -Less than CD-Quality, meaning 192Kbs or lower MP3 or other compressed formats, this is the minimum for listenable audio reproduction. An extreme example of this would be the low-bit movement, which is actually pretty cool.
Tier 1: -CD quality WAV or FLAC, and ~320kbs MP3/M4A/OGG for mobile listening.
Tier 1.5: -Approximately CD quality sample rate (44.1/48K) but 24 bit resolution.
Tier 2: -Higher than CD quality, 88.2/96K WAV/FLAC, always 24 bit.
Tier 3: -Stupidity. 176.4/196K sample rate, 24 bit or 32 bit float.
Tier 4: -Vinyl + magic turntables, solid gold cables, speaker crystals, etc.
The last one is obviously a joke, vinyl and tape are a different beast altogether from digital audio. But it is true, you can waste a stupid amount of money on obscure and expensive stereo equipment that is supposedly better than even the highest resolution digital system. That's up to your ears, and mainly your wallet whether or not you want to buy into it.
Tier 0 is serious though, I admittedly still have some 192kbs MP3s. They don't even sound that bad because of how well MP3 and other codecs can compress the audio data. One time I found out that a favourite album, which shall remain unnamed, was encoded as a 64kbs MP3. That's the amount of data is takes to make a telephone call! But to accurately represent a CD quality file, it takes a 192kbs or higher bitrate MP3. I use M4A myself, on one hand because I did a shootout and found it to be the closest to representing a CD quality WAV. But on the other hand, it's what iTunes uses by default, so you can chuck your CDs in your computer and it converts it nicely with the files all nicely tagged. (Minus a million geek points)
Tier 1 is "legit tier" meaning the highest that consumer audio is delivered at, as well as the lowest quality that is acceptable for professional music production. This of course means 44.1K/16-Bit, stereo WAV files. These are fine for production, if you are into sampling than you probably know the history of CD quality sampling. There were some early, much sought after samplers that sampled or stored data at slighter lower than CD quality, but that's beyond the scope of this post. The most sampled drum break of all time, the amen break, is widely available online as a mono CD quality WAV, ready for chopping up.
320kbs is the maximum bitrate that the MP3 format specifies. You can make MP3s at a 48khz sampling rate, but it's not really recommended. Firstly, they might not play in certain players, or they might get converted down to 44.1K anyways, probably by a dodgy algorithm. So you'll lose the 8.125% extra quality you've added (o no!) But also, you're increasing the sample rate while the bitrate is still the same, so an equal amount of data needs to represent more samples, thus lowering the quality to the same level. Basically, if you want to get the most out of your MP3s, you should adhere to the 44.1Khz/320kbs standard.
For other formats, you can get a bit higher than 320kbs, but your filesize will be slightly larger. OGG, a newer but very widely supported file format, can go up to ~500kbs, but I find it difficult to find reliable software to convert files to this format. It's not worth the extra hassle and disc space to get the most out of compressed audio. Maybe one day things will be better, and we'll all be using 500kbs OGG at 48khz on our future smartphones. Sounds utopian, which means it will probably never happen.
Tier 1.5 I added because there's a crossover, as well as a sweet spot in this area. It's for audio at 44.1/48K but at 24 bit resolution. For most people, it's not really necessary to have audio at any higher quality than this. You can rip a vinyl at this rate, FLAC it, and it will be the same size as a CD- quality file. That's what I like most about this area, you can have your cake and eat it too, and you won't get fat either! Well, your disks won't anyways. (Get it! FAT, disks! *cough*cough*) Anyways, I always recommend recording at 24 bit, even if you're using a single resolution sample rate like 44.1/48K. It will make life easier for you as a producer/mixer, if you're into that sortof thing.
Tier 2 is studio-quality. Most studios these days record at 96K/24-Bit, or even higher rates. I think it's overkill for a number of reasons, some more justified than others... But, this is what the pros do, so if you really want to be like them, than use double resolution sample rates like 88.2/96K and always 24 bit resolution. But you should probably have an external drive for your sessions, becuse all those tracks of high quality WAV/AIFF files are going to clog your drives up. A 88.2k/24-Bit file is 3x the amount of data as a CD quality file, per mono track. This is the main downside to using such a high resolution format. But chances are your interface runs at 96/192K, 24-bit, so if you really want to get the most out of your gear, than you should use this rate.
Tier 3 is where you get into serious overkill. A 192K/24-bit file is 6.5 times as large as a CD quality file. Totally stupid in my opinion, and in the opinion of alot of professional audio engineers. Yet for some reason alot of equipment runs at this rate, for what reason I'll never know. Everything I have read on the matter has been to the effect that 192Khz is an unnecessarily high sample rate. This is one of those cases where bigger does not = better. 96Khz is all that is nessecary for extremely high quality audio, higher than you'll ever be able to perceive with your own (likely damaged) hearing.
I have a personal anecdote to explain Tier 4. The singer in my Dad's band works at a company that sells serious audiophile-grade gear. The last time I saw him, he said they had a turntable that cost $100000! There was also a pair of cables that cost $15 grand. When I asked "Who would buy that?" the answer was of course "People with way too much money. They say 'Oh that's the best? I'll have that then.'" So, with that in mind... What would you do with $115 grand? I would spend 1% of that on a Technics SL-1200, than buy a bunch of vinyl. Than I'd put a down-payment on a house to put it all in, than buy a car to bring be back and forth from DJ gigs. Sounds utopian right?
Probably because it will never happen.
Until than, I'm keeping my headphones on.
