[Logsah]

  Usually, I leave my windows volume control around 50%, my volume control on my O2 at around 50%, and my gain switch on low gain.

 
 
Jesus, I usually have Win vol 100% / iBasso Boa 80% & high gain on..........listening to Dubstep!!!  

 
I'm going to die aren't I lol?
 
 
Ok clearly I need to re-look at my listening levels doh!

 

[cjl]

What headphones do you have? You might just have much, much less sensitive headphones than I do (which is very plausible, since I use Denon D5000s, which are fairly low impedance and definitely on the more sensitive side as audiophile headphones go).
 
EDIT: Oh, and you're also using a completely different amp. 80% on one amp is completely different from 80% on another amp, so you could be listening at the same level as I am for all we can tell from the information given. Looking at the specs on the Boa, it doesn't look like it has nearly as much power as the O2, so you aren't listening nearly as loud as you would be on an O2 with the high gain setting on at 80% (which would be pretty loud on the vast majority of headphones out there).

 

[Logsah]

  What headphones do you have? You might just have much, much less sensitive headphones than I do (which is very plausible, since I use Denon D5000s, which are fairly low impedance and definitely on the more sensitive side as audiophile headphones go).
 
EDIT: Oh, and you're also using a completely different amp. 80% on one amp is completely different from 80% on another amp, so you could be listening at the same level as I am for all we can tell from the information given. Looking at the specs on the Boa, it doesn't look like it has nearly as much power as the O2, so you aren't listening nearly as loud as you would be on an O2 with the high gain setting on at 80% (which would be pretty loud on the vast majority of headphones out there).

 
Audio Technica ES700 with Forza AudioWorks re-cable & ESW9 pads. [impedance 36 ohms]
+
iBasso D2+ Boa Amp/Dac / Output power：Up to 100mW+100mW into 32Ω / Gain: +3dB/ +10dB (AMP) 
 
 
 
Aww no dude I'm deffo listening to my music way too loud (raver child of the 90's here lol) 

 
For example before I had the V-Moda M80's and with everything turned up 100% and at 24 seconds into
this song for example the 'Pop or Bok' sound would feel like a tiny knome with a hammer inside my head hitting
me behind the bridge of the nose/eyes area lol 

 bad headaches afterwards etc.
 

 
 
The Youtube version doesn't quite go loud enough but there's a zippy download if you wanna
temporarily listen to it thru your player of choice with EQ etc. http://www49.zippyshare.com/v/42536243/file.html
 
I used Foobar with the 'Punch & Sparkle' EQ preset found here:
http://www.sevenforums.com/sound-audio/2477-foobar-2000-equalizer-presets.html
 
 
Any advice welcome'd yall 

 
(sry for mini thread hijack)

 

[Dark_wizzie]

You use HD800 with O2 at max volume and gain, your ears will liquify.

 

[cjl]

Well, those will be about 6dB quieter at the same voltage level than my D5000s, and as I already said, the O2 can output significantly more power than the Boa from what I can find. The Boa claims 125mW into 16 ohms, and assuming that's voltage limited, that means it can swing about 1.4V RMS at full power (and this is probably underestimating a bit - especially if your stat of 100mW into 32 ohms is accurate, since that's more like a 1.7V RMS signal). Into the ES700s, that would be 120dB for a 0dBFS signal at full power. However, at 80% volume and (probably) not a full scale input signal to the amp from the dac, you might be down at more like 100-105dB. That's still very, very loud, and potentially damaging to your hearing.
 
For comparison though, the O2, which is what I use, can swing about 4V into 25 ohms (my D5000s), which would be a full-power level of 134dB (!!!). It can also push  around 6V into 56 ohms (your ES700s), which is about 132dB. You would never want to listen this loud - it would almost immediately permanently damage your hearing (and possibly blow your headphones).
 
(For what it's worth, my D5000s are fairly loud on my O2 at 50% volume and low gain, with 50% software volume and playing that youtube video as the source. They are VERY loud (uncomfortably so in parts) with the O2 on high gain, still 50% volume both on the knob and in software I can't imagine turning it up to full software volume/80% amp volume on high gain, but as I said, that would be quite a bit louder on my setup than on yours)

 

[cjl]

  You use HD800 with O2 at max volume and gain, your ears will liquify.

I would believe it - the O2 could push a bit over 7V RMS into the HD800, which is the better part of 200mW and 125dB.

 

[Dark_wizzie]

Yeah, even running the volume knob to halfway without gain is going to damage my ears. I've seen some graphs showing the HD800 having impedence shoot up to ~640 ohms at 100hz. 
http://www.innerfidelity.com/images/SennheiserHD800B.pdf
 
But O2 can drive that?

 

[Logsah]

  Into the ES700s, that would be 120dB for a 0dBFS signal at full power.
However, at 80% volume and (probably) not a full scale input signal to the amp from the dac, you might be down at more like 100-105dB. 

 
Good man cheers, yup I'm still too loud but these are figures I can work it out from 

 

[SilverEars]

  Yeah, even running the volume knob to halfway without gain is going to damage my ears. I've seen some graphs showing the HD800 having impedence shoot up to ~640 ohms at 100hz. 
http://www.innerfidelity.com/images/SennheiserHD800B.pdf
 
But O2 can drive that?

True, although the specs say 300ohms, it's not true.  It varies and can shoot up to 600ohms.  You need to take care of that as the worse case scenario as it will clip if there isn't enough.  When I used O2 with it, it didn't sound right, not sure if it clipped.  I know my other amp it clipped, and it drives my 650 fine, and it can have something to do with the varying impedance as the 650's impedance peak is less than the 800's.  

 

[Dark_wizzie]

Here is the impedence graph for the HD800 (from Innerfidelity):
http://www.innerfidelity.com/images/SennheiserHD800.pdf
 
The guy from NW talk about O2 seems like it is designed to be able to run Beyer DT880 600ohm version as worst case scenario.
 

THD+N vs OUTPUT & MAX POWER ON AC: At 1 Khz with both channels driven here’s the distortion versus output on AC power into 15, 33, 80, 150 and 600 ohms. At 150 & 600 Ohms the output voltage was essentially the same at about 7.3 volts RMS. And even at about 200 mW of output into any of the loads the distortion is still below about 0.0025%! Maximum power is about 640 mW at 80 ohms. The power limits shown below exceed the power requirements established for the assumed worst case headphones (HiFiMan planars and 600 ohm version of the Beyer DT880):

The Hifiman planars... they don't require a lot of ohms, they just have low sensitivity. But the DT880 600ohm graph here 
http://www.innerfidelity.com/images/BeyerdynamicDT880600ohm.pdf
 
shows that the DT880 is definitely harder to drive than HD800.
The thing is though, that the impedence requirement spike to 640 ish? is at 100hz, which is a bass frequency. I'm just wondering if this can have an effect on the bass. One guy on headfi replied saying, maybe it's the rapid changes in required impedance that could cause problems? But I have no idea whether his idea has an merit.
 

 CLIPPING PERFORMANCE: Some amps become unstable when pushed to clipping for many reasons. Some op amps, for example, are prone to phase reversal when clipped where the output violently slams into the oppositesupply rail. Other amps exhibit ultrasonic oscillation when clipped. The O2 is completely clean into any load I tried and also exhibits very close to symmetrical clipping. This is one of those tests everyone should always run, and not just with a soundcard “scope”, so you can see any ultrasonic/RF problems. Here the O2 hits +/- 20 volts peak-to-peak at 10 Khz into 600 ohms on AC power on a 100 Mhz scope:

Based on what the guy from NW says I think he believes the O2 can drive regular 600ohm headphones, so a HD800 should really be covered no matter the frequency with no problems at all. 
 
Also I do not know of any other impedance graph for HD800s, neither do I know how accurate InnerFidelity's measurements are.
Personal experience with O2 is that the O2 can drive the HD800 effortlessly. But seeing the huge variation in impedance from frequency to frequency it's a little hard to know how the 100hz section fares but I don't think it's bad enough to be a problem, in my uneducated opinion.

 

[cjl]

  True, although the specs say 300ohms, it's not true.  It varies and can shoot up to 600ohms.  You need to take care of that as the worse case scenario as it will clip if there isn't enough.  When I used O2 with it, it didn't sound right, not sure if it clipped.  I know my other amp it clipped, and it drives my 650 fine, and it can have something to do with the varying impedance as the 650's impedance peak is less than the 800's.  

As far as an amp is concerned, a higher impedance load is an easier load. This is also why pretty much every preamp out there can drive a 10kOhm input impedance into an amp easily, but you have to have some pretty serious professional (or high end) amplifier to push any kind of substantial voltage swing into a 2 ohm loudspeaker. Since the amp is trying to act as a voltage source, it isn't going to clip if the impedance of the headphones is higher in a particular area - it just doesn't have to source as much current at those frequencies for the same voltage swing. The O2 can easily drive the HD800 well past any volume you'd ever want to listen at, and it will do so with zero audible distortion and perfect frequency response. As I mentioned earlier, the O2 can push around 7V RMS into a high-impedance load like the HD800 (and if you look at the designer's graph, you might notice that its voltage output vs THD plots look almost identical when driving an 80 ohm, a 150 ohm, and a 600 ohm load, and its THD drops and peak output voltage increases for higher impedance loads). I know people in high-end audio like to believe that a $150 amp couldn't possibly drive a $1500 pair of headphones correctly, but the measurements disagree in this case. I will admit though that my prior calculation is wrong - I forgot that Sennheiser specifies sensitivity in dB/1VRMS, not dB/mW like everyone else, so a 7.3V signal would actually only push them to 119dB, not 125 as I stated above. Of course, 119dB is still way more than enough.
 
As for the HD800 vs HD650? Assuming the manufacturer's specified sensitivities are correct, there really shouldn't be much difference between the difficulty of driving the two of them. Sure, the HD650 is a bit more sensitive, so it should be a bit easier to drive, but the difference should be on the order of a dB or two. Unless you were already really, really borderline with the 650, the 800 shouldn't be a problem for any amp that can drive the 650. How are you determining that it is clipping, out of curiosity?
 
Finally, as far as the amp is concerned, the most difficult load to drive well is actually a low impedance, low sensitivity headphone, such as the HE-6. To drive those properly, you need a large voltage swing and a LOT of current, and that is where you could well see a problem with the O2 distorting. It does just fine on the LCD-XC in my opinion, which is the hardest headphone to drive that I have ever tried my O2 with. The HE-6 is even harder to drive though, so I could envision it having some problems there. I don't have access to a pair to try them out, so this is purely theoretical. Actually, in many ways a moderate sensitivity, high-impedance headphone is the easiest to drive (which is probably part of why many professional monitoring headphones fall into this category). A super sensitive, low-impedance design like an IEM is really sensitive to noise in the amplifier circuit (which can be hard to eliminate entirely), a low impedance, low sensitivity design requires a lot of current (which can be hard to source without distortion), but a moderate sensitivity, high impedance design is not going to have a noise problem (unless you have a truly appalling amount of noise in your electronics), is not going to require much current to drive (which means things like output impedance and trace resistance on the board become unimportant), and the only real downside is that it takes a bigger voltage swing (and +/- 20V or so is easy to do when you have access to an AC power supply - it only really is a problem if you have to run off batteries in a portable player or something like that). So, if you know you'll pretty much always be using a desktop amp with high voltage power sources available, the high impedance, moderate sensitivity design is kind of a no brainer. I don't know where people got this idea that high impedance = hard to drive, but it's really not even close to correct (sadly, otherwise I'd be running my 8 ohm speakers off a tiny little headphone amp

)

 

[Dark_wizzie]

  As far as an amp is concerned, a higher impedance load is an easier load. This is also why pretty much every preamp out there can drive a 10kOhm input impedance into an amp easily, but you have to have some pretty serious professional (or high end) amplifier to push any kind of substantial voltage swing into a 2 ohm loudspeaker. Since the amp is trying to act as a voltage source, it isn't going to clip if the impedance of the headphones is higher in a particular area - it just doesn't have to source as much current at those frequencies for the same voltage swing. The O2 can easily drive the HD800 well past any volume you'd ever want to listen at, and it will do so with zero audible distortion and perfect frequency response. As I mentioned earlier, the O2 can push around 7V RMS into a high-impedance load like the HD800 (and if you look at the designer's graph, you might notice that its voltage output vs THD plots look almost identical when driving an 80 ohm, a 150 ohm, and a 600 ohm load, and its THD drops and peak output voltage increases for higher impedance loads). I know people in high-end audio like to believe that a $150 amp couldn't possibly drive a $1500 pair of headphones correctly, but the measurements disagree in this case. I will admit though that my prior calculation is wrong - I forgot that Sennheiser specifies sensitivity in dB/1VRMS, not dB/mW like everyone else, so a 7.3V signal would actually only push them to 119dB, not 125 as I stated above. Of course, 119dB is still way more than enough.
 
As for the HD800 vs HD650? Assuming the manufacturer's specified sensitivities are correct, there really shouldn't be much difference between the difficulty of driving the two of them. Sure, the HD650 is a bit more sensitive, so it should be a bit easier to drive, but the difference should be on the order of a dB or two. Unless you were already really, really borderline with the 650, the 800 shouldn't be a problem for any amp that can drive the 650. How are you determining that it is clipping, out of curiosity?
 
Finally, as far as the amp is concerned, the most difficult load to drive well is actually a low impedance, low sensitivity headphone, such as the HE-6. To drive those properly, you need a large voltage swing and a LOT of current, and that is where you could well see a problem with the O2 distorting. It does just fine on the LCD-XC in my opinion, which is the hardest headphone to drive that I have ever tried my O2 with. The HE-6 is even harder to drive though, so I could envision it having some problems there. I don't have access to a pair to try them out, so this is purely theoretical. Actually, in many ways a moderate sensitivity, high-impedance headphone is the easiest to drive (which is probably part of why many professional monitoring headphones fall into this category). A super sensitive, low-impedance design like an IEM is really sensitive to noise in the amplifier circuit (which can be hard to eliminate entirely), a low impedance, low sensitivity design requires a lot of current (which can be hard to source without distortion), but a moderate sensitivity, high impedance design is not going to have a noise problem (unless you have a truly appalling amount of noise in your electronics), is not going to require much current to drive (which means things like output impedance and trace resistance on the board become unimportant), and the only real downside is that it takes a bigger voltage swing (and +/- 20V or so is easy to do when you have access to an AC power supply - it only really is a problem if you have to run off batteries in a portable player or something like that). So, if you know you'll pretty much always be using a desktop amp with high voltage power sources available, the high impedance, moderate sensitivity design is kind of a no brainer. I don't know where people got this idea that high impedance = hard to drive, but it's really not even close to correct (sadly, otherwise I'd be running my 8 ohm speakers off a tiny little headphone amp

)

I am inclined to agree with you - What you say seems to correlate with NW person's writings.
How hard are LCD3s or HE500s to drive, I'm sure they are easier than HE6.
 
If higher ohms mean easier to drive, then why can't all amps just drive 600 ohms?

 

[SilverEars]

Well, I have a tube hybrid amp I use with the 650 and when I used it with the 800 it started to crackle at a certain volume level, so my guess was that it was starting to clip.  I had no problems like that with my 650.  I've also tried the 800 with my O2, and I recall it sounded worse than my 650(don't recall if it clipped or not), but I don't like listening to my 650 with the O2.  
 
I've tried O2 and my Beta 22 with LCD2 and HE-6.  There is noticeable difference in the sound, and I favor the Beta 22 as both of them sound tighter and has better dynamics. 

 

[ab initio]

If higher ohms mean easier to drive, then why can't all amps just drive 600 ohms?

Because you need enough volts to get loud enough. As a general rule, the higher the impedance, the higher the voltage swing needed to get the same loudness. Many sources like phones or ipods Peter out at 1.5 or 2 volts RMS which may not be loud enough.

Cheers

 

[SilverEars]

Because you need enough volts to get loud enough. As a general rule, the higher the impedance, the higher the voltage swing needed to get the same loudness. Many sources like phones or ipods Peter out at 1.5 or 2 volts RMS which may not be loud enough.

Cheers

This of course depends on the sensitivity of the headphones.  Even at 600ohms, if the sensitivity is high enough, it will be loud at 1.5 or 2 volts. In the case of Beyers, it's not the case so yeah, it need higher voltage, so the puny DAPs are not providing enough juice.
 
I think people generally think low impedance as easier to drive because lots of portable headphones are low impedance and they get loud, not because of the low impedance, but because of the high sensitivity.  
 
This is why HE-6 at 50ohms is still hard to drive because the sensitivity is low, which is quite different from most headphones specs.  That probably throws people off.