Running the HD650's... Ampless?

I highly recommend the Denon D2000. It doesn't need an amp. But... it depends on what you listen to. If it's like mainstream (assuming it's not extremely bass-heavy) music, the D2000 are the best at this. They are closed cans. HD650 are open cans so they don't isolate sounds both in and out. Also take a look at D5000 and D7000 as well.

You can look at the HD600 which isnt as amp dependent as the hd650. It also isnt as dark, laid-back and covers a different genre compared to the HD650.

"The HD600 is not leaps ahead in terms of pace, but sometimes it’s enough to make or break a music. Some people who listens to Progressive Rock and Metal would probably prefer the HD600 over the HD650. On the other hand, the HD650′s superior bass weight and impact is much better for Classical Symphonies, and also feels fuller for the slower Jazz and Vocal stuff."  -Headfonia.

obviously the Denon D2000s are also a great choice, basically a closed headphone legend but finding them is a bit difficult.

all these headphones are great headphones, as long as they are properly sourced.

p.s.

sell your beats :)

The HD600 and HD650 perform good without an amp but and amp does help. I use my HD600 without an amp all the time and the performance with and without an amp is not at all that large. Sure it's noticeable but it's not like it sounds bad at all.  I use my HD600 with my Zune HD all the time and it sounds great!

Quote:

Originally Posted by Zombie_X 
Sure it's noticeable but it's not like it sounds bad at all.  I use my HD600 with my Zune HD all the time and it sounds great!

What's the volume level on the Zune? One time the power went out, and out of boredom I just had to listen to some music, plugging my HD600 into my Creative Zen MX and iPod video. It was horrible with the iPod (audible clipping) and while I liked it with the ZenMX, it was at full volume and I only got 1 hour out a fully-charged battery.

The E11 will do for most headphones in that range :)

Why the preference for the HD 650? Have you heard them?

They are dramatically different from anything else you've mentioned, or that has been mentioned for you (except the HD 600) - they will very likely sound "bass light" or "dead" coming from the Beats or Bose QC headphones. The Denon AH-D2000 or AH-D5000 will be more of an "in-between" - you will get more detail, but retain the powerful bass impact and other "v-curve" attributes associated with most mainstream products. Regarding the Beats Pro, I haven't spent extensive time with them, but from what I have seen (I have had them on my 'noggin) - they are not as well put together as the images/materials would imply, and the sound does not fully justify the $400-some-odd price (although this is based on a very brief audition). They are much smaller in person than you might expect. They were not incredibly comfortable.

You can probably try the Bose and Monster products if you live near an Apple or Best Buy store; they often have demonstration sets. 

Regarding amplification for the HD 650, they do not require substantial power in order to perform, but they do require a driver that can deal with their impedance. Lots and lots of cheap/mainstream components will not deliver this (I know that the Walkman NWZ-A series can, I suspect that many desktop audio cards can, but beyond that it's up in the air - low-end roll-off is likely going to be the biggest issue). I would NEVER consider them for any form of mobile or work use - they provide no isolation, and will not only leak sound to everyone around you (which is annoying for everyone else), but you will hear everything else around you (and if you crank them up to "block" the noise, you'll damage your hearing over time). I would consider something else - the Denon AH-D2000 is not a bad suggestion. I've read good things about the Audio-Technica ATH-A900 as well, but have never heard them. Both of these are closed, and both of them include a native 1/8" jack to plug into your portable. The Denons can play very nice with mobile devices. 

Quote:

Originally Posted by Frequen C 

Would the FiiiO E11 drive the HD 650's well? I would prefer to get the HD 650's over any other headphone.

The FIIO E11 will drive the HD650s just fine.  (I have them both)  As a point of reference, I just sparked up the pair using my iPhone 4 with LOD cable and some Alice in Chains - Unplugged, and I only needed the volume at 40-50% and it sounded plenty powerful with excellent SQ. (and my hearing isn't good)  I also have a desktop amp but I use the E11 for both my 650s and m50s while sitting around on the couch or lying in bed.  Best of luck with your decision.

Again, how do you know the sound signature will appeal to you? Have you heard them?

I'm not attacking your decision, but it's impossible to know if a pair of cans is a "fit" without trying it. Be prepared to cycle a few returns. 

Since you want your opinion validated so badly, yes - the E11 will very likely work with no problem (and I mean this - I think this is also the general advice you've been getting from multiple people; are you expecting it to change if you ask enough times?). If you're using these at home, what's the problem with buying a proper desktop amp? (I've noticed in a lot of threads since my return, portable amplifiers are mentioned exclusively, as if AC power doesn't exist and we're all relegated to batteries). The Fiio E9 will admirably drive the Sennheisers (and most anything else I've plugged into it) to ear-destroying levels, and with good quality. I would contend that it's an equal to the CI VHP1/2 at a fraction of the price. If you have a desktop computer (what's that?), you may also consider a "headphone amplifier soundcard" or some sort of USB magilicuddy that has a decent headphone driver built into it. The HD 600/650 are not impossible to power, just remember that they're a 300 ohm load with an impedance peak around 100hz; whatever you're plugging them into better be able to deliver into that load. The Denons, by contrast, are 25 ohms and fairly level in their FR impedance - they're also more sensitive. 
 

Quote:

Originally Posted by Frequen C 

I will consider the Denon's, but the sound signature of the HD 650's seems like it will appeal more to me.  I understand that using these in the office is not a great idea; but I would really like them for home use. Does anyone else think the FiiO E11 is a sufficient amp, or should I look at something different?

As others have said, the HD600 and HD650 are both open. So if you're planning on using the headphones you get in an office-type setting, then I wouldn't bother considering them.