[ZBoneCapone]

Quote:

In a studio setting, that DAC becomes even more important than an audiophile setting. The DAC's drivers, specifications, and features are what you want to look at rather than concerning yourself with sound quality. Ideally, a DAC should not "add" its own flavor to the signal. If you get EMI, hiss, or jitter, and it's not mentioned in the specfications, then they're technically flaws or deficiencies (i.e. cheap DAC knock-offs, unshielded parts, roll-offs, etc.). Stay away from companies that don't stand behind their products (I'm looking at you EMU).
 
As for headphone amps, their main job is to amplify the line signal for harder-to-drive headphones. The rest are features, specifications, and aesthetics.

So can you give me a hard and fast rule for "harder-to-drive" headphones? What impedance is hard to drive? Over 80ohm? 100? Secondly, is there a situation where I only need a DAC but no amp? Neither? Both? Sorry for so many questions, but honestly no one is answering my questions directly

 

[Fearless1]

Quote:

In other words headphones have a sound signature and so do amps... I worded it terribly but it wasn't that bad.

Yeah, I understand what you were trying to say, the "huh" means I do not agree with it based on the fact that there are a multitude of other variables that go into an amps sonic signature. The fact that an amp has tubes does not make it sound one definitive way. My warmest amp is solid state, and I can roll some tubes in my LYR or EF-5 that make it sound very cold and sterile.

 

[Kirisame Touko]

usually its harder to drive when the impedance is around 80 ohms +. I think it would be good to use atleast a weak amp. But even thats not absolute. The architecture also changes these factors considerably. For example it is significantly easier to drive 600 ohms DT 880 compared to HE-6 even though HE-6's impedance is lower than 100.

There are also other cases where some phones are suprisingly hard to drive like AKG 7xx. (although i can be wrong)

The point is around 80 ohms sure, generally a good idea to have atleast a weak amp (for most dynamic drivers) but this is still a very loose rule.

If you are using electro stat or othodynamic phone the amount of energy requires changes completely despite its impedance ohms numbers when your comparing with normal dynamic phones

 

[Eric_C]

Quote:

So can you give me a hard and fast rule for "harder-to-drive" headphones? What impedance is hard to drive? Over 80ohm? 100? Secondly, is there a situation where I only need a DAC but no amp? Neither? Both? Sorry for so many questions, but honestly no one is answering my questions directly

I think folks are answering your questions pretty directly, but you didn't ask about stuff like "what impedance is hard to drive" until now.
 
Rules of thumb will get argued over very quickly here. You have a specific headphone in mind already, so you might as well look at what that headphone needs. Here's a review that talks about the 702 and how to amp it: http://www.kenrockwell.com/audio/akg/k702.htm

 

[Brooko]

@ OP - this might help.  It relates the K701 (essentially same drivers as your Anni) with a Senn HD650.
http://lsirui.wordpress.com/2009/04/15/k701-vs-hd650-electrical-measurement/
 
And to Vloeibaarglas - I'm actually pretty sure the advice given by Eric_C was spot on (as a general rule of thumb).  Here's some more info (http://www.head-fi.org/a/headphone-impedance)
 
I'm not an EE - but my understanding is that a high impedance headphone like the Beyer DT880 600 ohm require a higher voltage (because of the impedance) to deliver enough current to the voice call to adequately create the ideal magnetic field.
 
At the other end of the equation - the K701/K702/Q701 & derivatives are relatively low impedance - but not very efficient.  They require a lot of current to reach a specified volume level.  In this case - throwing a higher voltage at it won't necessarily help - because they are lower impedance anyway.  But more current is required.
 
If you really want some better info from the guys that really know - try posting the same question in the Sound Science forum.  A lot of the guys there are EEs or have an EE background - and can explain the science a lot better.
 
FWIW - whilst my K701 sound great with my LD MKIV - they acutally perform better with my SS NFB-12 (to my ears).  the Beyers I have are the opposite.

 

[Seamless Sounds]

I'll see if I can clear this up

Originally Posted by ZBoneCapone /img/forum/go_quote.gif
 
When do I need one and why?

Every digital device has a DAC and amp. I'll rephrase your question as "do I 'need' better ones?" It depends. I'll be honest, I'm not that kind of guy who spends $$$$ on expensive amps, DACs, and cables primarily for sound quality alone. If I were to spend money on recabling my headphones, then it's for length, durability, and aesthetics; Justifying it solely on SQ "improvement" is something I'll never do. I prefer to spend more of that money on different headphones/speakers to acquire different sound signatures than amps and DAC. I can't tell night and day differences between amps* vs amps* and DACs vs DACs. In this case I look at their features, specifications, and aesthetics and also see if they match up with my headphones.
 
*There are amps that may color the sound or have roll-offs in them, most notably some tube amps. However, you'll have to make the choice between sound reproduction (unaltered sound) or coloration (altered sound).
 
First start by creating a list of criteria on what you need or want.
Are you comfortable with tube rolling and maintenance? If not, go with a solid-state. However, solid-states focus more on sound reproduction than coloration. You'll have to weigh your priorities.
 
My headphones are K701 and in the future, HD800.
 
So I need an amp that can:
 
1. fully reproduce the sound as best as possible
2. come with a bass-boost feature to give the K701 a boost
3. Can drive low and high impedance headphones without distortion or problems at higher volume
4. Require little to no maintenance
5. Budget <$600
 
Running these cans out of the back of a PC did not meet some of those criteria. That's when you upgrade. This lead me to AMB's M³. On the other hand, If running them out of your PC does not break any of your expectations, then don't buy an amp. Although I sure do love the feel of a knob when I'm adjusting volume.
 
I also got the σ11 power supply.  Do I "need" it over the less expensive wall wart? Not at all. It was something that I "wanted" to have. Why? I enjoy DIY and wanted to give it a DIY PSU made for M³ from AMB, no more no less.
 
As for the DAC, I used to have the EMU 0404 USB, but I sold it. It was sold because it failed my expectations. It did not play smoothly in DAW applications. The drivers were terrible and sometimes the audio drops out. If I wanted a DAC that just plays on iTunes, foobar, or winamp, then I would've kept it. SQ-wise, many of them are so similar that the differences are negligible. Hence why I said to focus on features, specifications, and aesthetics. If you want a DAC that has a low-pass filter starting at 90khz, but want to spend $1000 more for one at 100khz, be my guest. I won't. It's an upgrade in specification, it's better, but not a priority for me.
 
tl;dr
So the point is, this applies to ANY product. When something doesn't meet expectations, that's when people upgrade to something better in order to meet those expectations. But you'll have to be consciously aware that something is not meeting your expectations before you decide you want to upgrade; it doesn't work the other way around. Everyone's expectations are different hence why I said it depends.

 

[Seamless Sounds]

So ZBoneCapone. If you want to listen at loud levels out of an ipod using ortho headphones and you notice it's still not loud enough at max, it hisses, and it distorts (expectations failed), that's when you upgrade (expectations met). If you notice the bass response is sloppy out of a netbook compared to playing it through a headphone amp that provides an improvement in bass response (placebo or not), then by all means upgrade. It's the same with folks who think 128kbps is fine and others who want no less than 320kbps. One is happy as long as expectations are met. Someone who listens only to lossless will expect lossless. If he/she is made to listen to 128kbps, they'll cringe, while others say "what's the big deal?"