Do I even need a headphone amp? I'm completely confused with all this technical jargon... could someone just tell me...

Total noob... I'm a geek (went to school and worked in IT for a number of years), but I can't wrap my head around the whole electronics side of this...
 
Just picked up the Sennheiser HD 280 Pro

1. [size=small][size=x-small]Impedance - 64 ohms[/size][/size]
2. [size=small][size=x-small]Long-term max. input power - 0.5 W[/size][/size]
3. [size=small][size=x-small]Frequency response (-10 dB referred to 1kHz) - 8 Hz - 25kHz[/size][/size]
4. [size=small][size=x-small]Sound pressure level - 102 db and 113 dB / 1 V rms[/size][/size]

 
Question 1 - Would the fiiO e6 be beneficial for my set-up?

Question 2 - Would the cMoyBB v2.03 Headphone Amplifier be a better choice?

Question 3 - What's the benefit of connecting to my iPhone via 30-pin dock connector vs. the 3.5 mini jack?

Question 4 - What would a DAC do for me and my listening experience?

Question 5 (somewhat unrelated) - I'm just using iTunes with the default file format to listen to music. Could someone point me to an article or online post regarding the best way to "upgrade" my files and/or player?

Set-up - Listening to music via my 3GS iPhone or MBP while working on the computer at a noisy coffee shop or a quiet library. Type of music is everything under the sun.

Notes - I read somewhere that the voltage of the e6 isn't sufficient for higher impedance headphones... but then I read somewhere else that the e6 doesn't really add anything to the iPhone/MBP.... but then I read even elsewhere my iPhone can't push the 280s enough or to their intended baseline (my phrase - hope it makes sense).

Online quote - "For most headphones with high sensitivity the E5 should be OK. In short, the E6 is best used with headphones rated at a minimum of 108 dB/Volt or 97 dB/mW." -NwAvGuy

Any help would be appreciated... Thanks.

The amplifier's goal is to take the input signal and produce a copy of it on the output (optionally scaled higher or lower, aka amplified), to send to the headphones.  In practice you can't produce a perfect copy, particularly when the output is connected to a headphones load, which has relatively low impedance and thus requires some non-trivial current.  Different headphone amplifiers have different internal circuit layouts (and components), and hence real-world performance may be different.  Depending on the load (headphones) and amplifier, the difference may be anything between obvious and so slight that expensive precision instrumentation has a difficult time discerning any difference, let alone human hearing.
 
People get dedicated headphone amplifiers because (1) in some situations they can improve the sound quality noticeably over whatever it is that's currently being used, (2) they may be able to provide more power, which is necessary to play certain headphones at a reasonable volume level, (3) they may have some sound processing features like bass boost or crossfeed that for some reason the user doesn't want to or can't do in software, and (4) they're shiny, and everybody likes shiny.  Are you looking for more volume (2) or not?  I would think not, with HD 280.
 
The iPhone has an internal headphone amplifier of decent quality, in the grand scheme of things.  If you use the 3.5mm jack, you are running the signal through the internal amplifier.  If you use the dock connector, you're getting the signal before it's passed to the internal amplifier.  If your goal is to run to an external amplifier, it's better bypass the internal amplifier, as the extra step is going to just degrade the sound quality...very slightly.  In practice it's not really anything to be worried about.
 
The quality of the FiiO E6 and CMoy BB are probably not very significantly higher than the iPhone internal amplifier.  However, both do have bass boost options, if you're interested in that.  But if you think it would be a hassle to lug around another device, it's probably not worth the effort and money.  Headphones and the source music make a lot more difference in the sound, and it's not like the HD 280 is the best thing out there.
 
iTunes default file format if you rip from a CD is about 256 kbps AAC these days, right?  That's plenty fine in general.

Thanks for the reply.
 
I have a few more questions... and please assume I'll be purchasing the cMoyBB (as sold).
 
1. If I connect via the dock connector instead of the 3.5mm jack (in order to bypass the internal amplifier), there's no way to power my iPhone and thus my battery will be sucked dry quicker, no? I ask this out of ignorance, assuming it takes more power to play music via the doc connector then the audio jack.
 
2. If I want to use the cMoyBB and my source is my MacBook Pro, wouldn't I need to go out the USB port in order to bypass the MBP's internal amplifier? If so, is there a simple usb to 3.5mm jack cable/dongle to buy?
 
3. I would like just a touch more bass with my 280s, without increasing the overall volume to get it, and thus my reason for looking into the cMoyBB. However I would be losing the opportunity to integrate a DAC into the process. Is this a trivial matter considering my setup isn't audiophile quality?
 
4. So just to reiterate - If I'm using my iPhone I will connect a fiio l3 or l9 to the phone's dock connection, connect the LOD to the cMoyBB, and connect the 280s to the cMoyBB. On the other hand if I use my MBP, I can either connect the cMoyBB via some sort of USB to audio jack cable?? or a Toslink Audio Cable?? or just a standard 3.5 audio?? However with the Toslink or standard cable, I will be amplifying an already amplified signal... which isn't wise.
 
5. My music is mostly downloaded from iTunes, so the files are in the standard format Apple gave them to me when I purchased them.
 
 
Thanks again

Also... someone else posted this on another forum - "With any model iPhone, there is only one brand that currently bypasses the internal DAC using the 30-pin dock (Fostex HP-1). It is a very pricey DAC/amp combo. Every other DAC or DAC/amp, even if it takes the signal from the 30-pin dock, is using the phone's DAC and is re-amping the signal. In practice, this is not a bad thing, but don't get into it thinking that just by using the dock you will bypass all of the phone's internal sound hardware."