the samsung stuff is cheap and pretty good, headphones can make more of difference over bit rate as the human ear cant tell the difference once you go beyond 128. recoding to wma and 48 (reduces the files from 8mb to under 1 for a song) I find is enough for everything I do and allows me to use players which take AA batteries. I used to send out samsung yepp and Iriver players to friends in basra.
some of the personal dab units have players in them now which is handy if you listen to digital.
got a solar powered one too which takes mini sd cards on top of the 1gb it allready has.
Particularly in the very highs (16-20kHz) and very lows (50Hz downwards) it can be quite clear.
What you may be thinking of however is the DACs in the mp3 players. Many mp3 players are fitted with such poor DACs (digital to analogue converters) that 128 is not audible from anything else.
128kbps equates to a sample rate of 8kHz which is 1/5th of a CD sampled at 44.1kHz. Problem with an 8kHz sample rate, is whilst it can capture an instrument producing a 16kHz signal, it will only record 1 in every 2 full cycles of the wave. A 44.1kHz sample rate can capture not only each cycle of the wave, but also intermittent points within it.
As a result of this, most mp3s include dithering adding noise around the wave to make your ear think there is more detail in there than there actually is. As you would do with a photo.
If you enjoy your music, I would go with at least 192kpbs but preferably 256 or 320kpbs. Using variable bit rate encoding is clever as it looks at the material it's encoding and works out if it's worth the effort of applying 320kbps encoding or whether an identical result could be achieved at 256.
You are correct however in saying that headphones have a far greater effect on the sound than the bit rate. For in-ear, Shure are my favourite (although no longer available in HMV, have to do the internet thang) but the Sennheisers are also good. Both companies produce IEMs (in ear monitoring) for professional singers and performers and thus understand the technology well. I have fired live 7.62 with Shure in-ears in and they offer almost as much noise reduction as the issue ear plugs (that be - the issued green&yellow christmas trees, not the yellow foam things).
my mp3 player knowledge is pretty poor, I don't have one. I have an iphone though. I just know a fair bit about audio.
Currently listening to Mark Knopfler at 2304kbps and it is definitely an audible difference to 128kbps.
if you are in a quiet room listening through expensive kit then yep it can make a difference, in most of the scenarios you end up listening to the music though its more background noise to pass to the time and just having the music is enough to cheer you up regardless of the rate its encoded.
I spend 5 years in a factory with my ears permanently in and I went from cd's to mp3's in various players, mediums, bit rates and headphones. outside and inside amplivox. also a lot of digital radio as fm is useless in gloucester for some reason. growing up with vinyl, tapes and cd's in walkmen, wogboxes and expensive stereos though I know what is a reasonable sound and the lowest bitrate I would go for is 48 but 32 is acceptable and like listening to the radio or a tape. the main thing is it means you can fit enough tunes on there to keep you busy all week without repetition on a 1gb player. if you encode the cd's as complete albums rather then individual songs you can halve the size of the files and get an album to around 20mb or less as a big chunk of data is the encoding information at the head of the track (so I'm told). audio books and radio shows can go even smaller and 32 is ideal, I've even downloaded some at 16 and they are still audible.
I have noticed that people who like going to live music are even less fussy and you can play them music to a pair of tin cans wired with string and they are happy.
I have three sets of music, one is the standard huge bitrate and sits on a network hard drive 212gb last time I checked and more than I could ever listen to. I encode it and chop it down to size for laptop and mp3 player use which is the usual means of listening. I go through headphones like no bodies business so tend to get creative headphones off ebay for around £1.50 a pair and 10 sets at a time as sometimes I can break 1 or 2 pairs a month. they hold their own to my koss and jvc kit and I dont mind losing a set or giving them away at that price.
I used to deploy with a small bag full of tapes and a walkman so i know that sanity can just equal 6 or 7 good albums, I'd rather buy two smaller mp3 players so I have a spare than rely on one big one which might and often does fail, currently its battery faults which are killing off millions of players so something which can run off regular ones is handy even if they might be a bit squarer than the fancy ones. they are also easier to fix when you knacker the headphone socket as they can be fixed unlike apple stuff which is w@nk.