Does anyone have Beats headphones who can tell a difference between lossless files and mp3 at a 320 bit rate?

Ahh, the widely disputed question of whether or not there is an audible difference between lossless and an mp3 file. I won't get into that, but I will give you what I think about some headphone brands. Grado makes some fine headphones though they aren't completely true to the music, as in although they sound nice, no, they don't reproduce the music to how the artist intended. Though there are those times when you want to jam and not care about the fact that they aren't technically what the artist recorded, (one instrument may stick out more than the artist intended, you tweak with this with EQ) you may want headphones that reproduce the music closest to the actual sound. Dennon makes some good closed headphones, that sound more like open headphones (with closed headphones sound won't leak out, with open sound will leak out, though open headphones generally tend to sound better). Koss makes some fairly decent sounding headphones. So does Sennheiser. AKG is another good manufacturer. There are manufactures that beat Bose in every aspect except noise-cancelation (look into JKG), and there is good sounding noise-cancelation headphones out there, their cancelation just isn't quite as good as Bose. Do some research yourself, see what you think, part of it is personal preference, part of it is how accurately headphones can reproduce the music.

Some tips to know when looking into headphones: the lower ohms and sensitivity, the easier it is to power the headphones, the higher the more power you need, this will be a factor in what you have to power your headphones, you may need to invest in a headphone amp if your going to use your ipod or mp3 player. What should be one of your main considerations when choosing headphones is frequency response, 20-20 is the full range (though the actual hearing range of the human ear is disputed, this is the most widely accepted range). For the fist number you want anything 20 or below, for the second you want 20 or higher. For instance 16-30 (not that your going to hear anything above or below 20, but many headphones will still be capable of reproducing sounds above or below 20 hertz). Back to open and closed headphones, closed headphones can sound like open headphones and vice versa, it just depends on the headphone. Also they may talk about the amount of time you can listen to the phones before ear fatigue sets in, this just refers to the amount of time you can listen before you grow tired of hearing the music.

In terms of sights to look to for headphone reviews try Cnet, Headfi, anythingbutipod, and just try a google search for headphone reviews and see what you get.

I've looked into a ton of headphone reviews and learned quite a lot about them in the process, I hope this helped.

I have bad news for you. In scientific blind listening tests that we're performed. No one was able to tell the difference in audio quality/fidelity between a 256kbps and above MP3 file, and a audio CD containing the same song. And even well respected audiophiles failed the tests. No one could hear an audible difference. Going below 256kbps though, the audiophiles noticed a drop in quality right away! And the tests we're performed using professional studio headphones so they could hear the full fidelity of the songs that we're being performed. That's not to say the CD did not sound better, because it did acording to the computers that monitored the frequency response ranges and all. It just proved that humans have limited hearing capability. Are ears themselves are the limiting factor. And even if we think we can tell a difference, no one really can. It's are brains that trick us into thinking one sound, sounds better then the other, when in reality it really doesn't.

Now I have used Bose headphones before, and all I can say is that they are wonderful bliss on the ears.

I haven't tried the Beats before though. But remember that more expensive doesn't mean that they will sound better. Bose has a great reputation for quality, but of course they will be about quadruple the price of ordinary headphones. But in the end, you won't be able to tell the difference between a 320kbps MP3 and a FLAC file.