So, I did a sound test using a FiiO headphone amp (was around $99) and Shure 325s:
Same CD source, one converted to standard lossy compression via iTunes std setting, one to FLAC using Audacity. I listened to the iTunes version using only the iPhone out and to the FLAC via the headphone amp.
Tracks included some industrial, some PanSonic, singer songwriter stuff, and vocal trance.
I didn't notice any difference.
I won't lug around over the ear Grados with me and a headphone amp that costs more than my iPhone, but, in your experience, do you actually notice any difference? Ever?
Btw. I don't care much about description such as warmth, presence, or soundstage, or other oblique semi-religious descriptors common on audiophile sites.
Techno starts with a capital 'T', as in TB-303 and TR-808.
Excluding all oblique semi-religious descriptors..no..I honestly don't notice a difference while playing stuff back either. I could be wrong about this, but don't iTunes "do some sort of "normalization" or something when you upload stuff to them..similar to what Sound Cloud and other sites do? If so, then that might make some sort of difference..not really sure, tbh.
The other thing is it might be a more balanced test if you take the same source (CD / track..preferably something of your own, as you know exactly how that should sound..) and convert it from WAV to both formats using the same audio converter..or even a number of audio converter programs..just to see if the converter is making any difference to the end sound you're listening to.
Honestly dude, whatever Pandora and Amazon Music stream at is good enough for me. Even when listening on my home hifi (not the greatest, but certainly higher quality than your typical big box store standard surround system) I think the streaming quality sounds fine. Compressed files tend to most noticeably loose low end, or so I have been led to believe.
I'm not saying there isn't a difference, but it isn't enough to make me worry about lossless files and the like as I basically never listen to music for enjoyment on anything playback system that would really take advantage of the difference.
MP3 320kbps sounds pretty damn close to lossless audio, and 95% of my music in my iPhone is lossless AIFF format ripped from CDs, so that's saying something. Since AAC is pretty much a better MP3, I guess you could say that you don't really need anything better.
I do make sure that the music on my iTunes is lossless format, since you can ask iTunes to convert the music to AAC format when you transfer your songs to your phone.
I notice the difference, since I can hear out to 22k and mp3 cuts out at 16k or less. Assuming it's been rendered well and there's no aliasing (which really bothers me), I can't hear the space quite right. Everything sounds a bit more muffled and mono to me. But some songs (Grum's first album) mix around that just fine. I don't though....
Even if it sounded like a mild wall of static over my converts, I'd still be grateful to save that much space. If I have to bend over and listen closely to pretend like I'm hearing a difference, I'll just call it a wash and an excellent space-saver.
Really, on consumer-level buds and cans you're probably not going to notice much difference with high bitrate MP3 up to wav format. Get these sounds in a treated studio with diffusers and proper monitors, you'd probably hear some top end roll-off and/or artifacting in cymbals, loss of clarity in the hi-mids and probably just an overall compressed feel to them. also, can depend on the source conversion codecs, hardware it's being done on etc. FTMP though, I agree you can't really tell especially if not trying to notice.
You have to be extremely familiar with tunes to notice differences.
But after you've been trained or educated to notice the differences, you'll notice them more and more. But usually you have to know what you are listening for.
For example, plenty of tunes will sound just fine as M4A (AAC) or OPUS, but as soon as you listen to the FLAC of the actual CD, you can hear more bass, wider imaging, clearer cymbals, deeper thumps, more stuff vibrating the room.
For casual listening, it's not a big deal, but for audiophile analytics it's actually worth it to stick with lossless as much as possible.
And in terms of sanctioned listening tests, quality these days is about like this: (best to worst, for 128 kbps and above)
WAV/AIFF/FLAC/ALAC --> OPUS --> M4A/AAC --> OGG/VORBIS --> MP3
That's according to scientific group listening tests. I personally agree with it, too.
And of course, if you can listen on an actual stereo or DAW with pro monitors you will notice a lot better. And be sure to have your speakers in the right place of the room horizontally and vertically.