[chewy4]

I never got the more power = better thing. It's not like you're actually using all the power the amp has.

 

[MrMateoHead]

Quote:

 
Great write up! I think with more voltage and power, and maybe some burn-in too, you'll see that the he400 can be quite "thumpy." I was using the Little Dot MKiii with some sweet mullard tubes to drive these cans, and the bass was great in almost every way--I had no complaints whatsoever. But when I started to use an old kenwood receiver to power the he400s instead, my jaw dropped: now the bass sounds positively  extraordinary! I said something to this effect earlier, but I think I should say it again: properly powered, the he400 has as much bass presence and thump as my Denon D2000s (which are widely reputed to be great headphones for bass)--only the he400's bass is way cleaner, with zero mid-bass bloat. Who knows? Maybe my he400's just have good synergy with this crazy receiver of mine. With that in mind, I'm not saying the difference between my various setups is not night and day, but now that they have real power, I would say that my He400 has crossed a threshold, so to speak, and in doing so, I think I have realized their full potential. 

I am going to try an Onkyo receiver later. My ears are on break. Below is a table showing expected SPL at different power levels, in this case, mWs, based on the published spec of 92.5 dB/mW. Something between 512 mWs and 1 full watt are needed to hit around 120 dB, which I think provides more than enough headroom for movies and other HDR recordings (which I find my current power lacking right now). 500 mWs is the minimum power I would guess is needed to go from quiet to riot on practically anything I throw at these.
 

mWs	SPL / mW
1	92.5
2	95.5
4	98.5
8	101.5
16	104.5
32	107.5
64	110.5
128	113.5
256	116.5
512	119.5
1024	122.5
2048	125.5
4096	128.5
8192	131.5
16384	134.5
32768	137.5

 
The question is, how many AMP/DAC combos or otherwise are affordable, sound good, and have these kinds of guts too? The Amp would have to make this power at 35-50 Ohms (test results seem to consistently place the HE-400 at 50, not 35 Ohms). Alternatively, this seems to require amps of up to 4-5Vrms (120 dB), which rules out most portables. The JDS Labs Objective 2 is the early best option so far, which is rated at 613 mWs @33 Ohms (355 mW @150) but up to 7Vrms. Power output seems optimized for lower impedance loads, and the HE-400 may fall too far out of the range. The Fiio E9 has the power, but is more of a "dock", and output impedance is high (10 Ohms). The Schiit Asgard has enough juice, according to an Amazon customer, but is rated 1Vrms, max 7Vrms, and I have no idea the mW output. The Audio GD 12.1 is a beast, but I still don't like the website and the cost with shipping is probably closer to $300. I am putting a constraint of $100-$200 dollars on this pursuit, since I don't think amps should cost more than the speaker, and I am broke anyway. Also, it has to be laptop friendly. I really like that the JDS labs uses a 3.5mm input, for example, since that is typical PC. USB interface is also convenient. Anyone want to throw out some ideas? I am all ears.

 

[MattTCG]

I'm not an expert here...far from it. But from my experience, a good amp with adequate power plays headphones that are matched well nice and full at 10:00 on the volume pot. Once you get into the 1:00 and 2:00 range, to play at that same volume on other amps, it gets sloppy with less dynamics, transparency and decay. 
 
The lyr is a good example of this to me. It plays effortlessly with full sound at 10:00. The sound is dynamic and not just loud. Even when listening at softer levels, all the details and subtle nuiances are present. Sometimes I like to listen "soft" and the lyr does that wonderfully, where my fiio e09 didn't. 

 

[Scyy]

Quote:

I'm not an expert here...far from it. But from my experience, a good amp with adequate power plays headphones that are matched well nice and full at 10:00 on the volume pot. Once you get into the 1:00 and 2:00 range, to play at that same volume on other amps, it gets sloppy with less dynamics, transparency and decay. 
 
The lyr is a good example of this to me. It plays effortlessly with full sound at 10:00. The sound is dynamic and not just loud. Even when listening at softer levels, all the details and subtle nuiances are present. Sometimes I like to listen "soft" and the lyr does that wonderfully, where my fiio e09 didn't. 

What position did you have for the he-400 on the asgard? I need a good 11-12 to get to a level I really like with my HE-400's on most songs.

 

[jerg]

Quote:

I am going to try an Onkyo receiver later. My ears are on break. Below is a table showing expected SPL at different power levels, in this case, mWs, based on the published spec of 92.5 dB/mW. Something between 512 mWs and 1 full watt are needed to hit around 120 dB, which I think provides more than enough headroom for movies and other HDR recordings (which I find my current power lacking right now). 500 mWs is the minimum power I would guess is needed to go from quiet to riot on practically anything I throw at these.
 

mWs	SPL / mW
1	92.5
2	95.5
4	98.5
8	101.5
16	104.5
32	107.5
64	110.5
128	113.5
256	116.5
512	119.5
1024	122.5
2048	125.5
4096	128.5
8192	131.5
16384	134.5
32768	137.5

 
The question is, how many AMP/DAC combos or otherwise are affordable, sound good, and have these kinds of guts too? The Amp would have to make this power at 35-50 Ohms (test results seem to consistently place the HE-400 at 50, not 35 Ohms). Alternatively, this seems to require amps of up to 4-5Vrms (120 dB), which rules out most portables. The JDS Labs Objective 2 is the early best option so far, which is rated at 613 mWs @33 Ohms (355 mW @150) but up to 7Vrms. Power output seems optimized for lower impedance loads, and the HE-400 may fall too far out of the range. The Fiio E9 has the power, but is more of a "dock", and output impedance is high (10 Ohms). The Schiit Asgard has enough juice, according to an Amazon customer, but is rated 1Vrms, max 7Vrms, and I have no idea the mW output. The Audio GD 12.1 is a beast, but I still don't like the website and the cost with shipping is probably closer to $300. I am putting a constraint of $100-$200 dollars on this pursuit, since I don't think amps should cost more than the speaker, and I am broke anyway. Also, it has to be laptop friendly. I really like that the JDS labs uses a 3.5mm input, for example, since that is typical PC. USB interface is also convenient. Anyone want to throw out some ideas? I am all ears.

Very informative post, thanks for the writeup. This is the most intriguing part of HE400s setups so far for me - figuring out what (if any) budget setup could actually bring it close to its full potentials in terms of power.

 

[Fearless1]

Quote:

I bet the Fiio and O2 gives them more power than the headphone out of most receivers.

Well the thing is I do own an O2, E-09 and E17. So no, as compared to a vintage receiver where the  headphone out is driven from the same power amp section that drives the speakers it is not even close. The O2 is a fantastic little amp, it makes my D7ks sing, but it does not do the HE-400 any justice to my ears.

 

[MattTCG]

Quote:

What position did you have for the he-400 on the asgard? I need a good 11-12 to get to a level I really like with my HE-400's on most songs.

 
The Asgard was two clicks more. I listened at about 11:00-12:00 on it as opposed to 9-10 on the lyr. 

 

[TMRaven]

Well the thing is I do own an O2, E-09 and E17. So no, as compared to a vintage receiver where the  headphone out is driven from the same power amp section that drives the speakers it is not even close. The O2 is a fantastic little amp, it makes my D7ks sing, but it does not do the HE-400 any justice to my ears.

So you're saying those receivers are throwing 100 or so watts into your headphones?

 

[chewy4]

I usually listen to my Asgard at like 30-40% for extended listening sessions. Rarely go up to 50% for sessions longer than an albums worth. Tons of headroom with it.
 
Although for certain recordings, especially non-soundboard live recordings, I bring it up about half way, maybe a little more.
 
EDIT: At least if I'm remembering correctly. I put it sideways so it's hard to tell...

 

[MrMateoHead]

Quote:

Very informative post, thanks for the writeup. This is the most intriguing part of HE400s setups so far for me - figuring out what (if any) budget setup could actually bring it close to its full potentials in terms of power.

Using the power of math (thanks to other members), I have a rough idea of a few amps:
 
TI TPA6120A2 chip (found in some high end sound cards, 10 Ohm output):

Impedance	Output
16	1,160 mW
32	890 mW
50	120 mW
600	79 mW

Schiit Asgard (1 Ohm output):

Impedance	Output
16	2,710 mW
32	1,440 mW
50	942 mW
600	81 mW

Audioengine D1 (10 ohm output):

Impedance	Output
32	72.3 mW
50	55.7 mW
600	6.5 mW

 
Perhaps as expected, higher output impedance has a huge impact on power output as the headphone impedance goes up. At 50 Ohms, even a good performer like the TI has fallen on its face in terms of reaching our 500 mW level. Notice that the Asgard maintains big power through 50 Ohms, but at 600 would be down to an estimated 81 mW. First key spec then is a minimum output impedance! Unfortunately, I haven't found a combination of higher voltage / lower output impedance yet other than the Schiit and the JDS Labs O2.
 
Hifiman should really work on reducing headphone impedance to about 32 Ohms, maybe even less.

 

[MrMateoHead]

Quote:

Well the thing is I do own an O2, E-09 and E17. So no, as compared to a vintage receiver where the  headphone out is driven from the same power amp section that drives the speakers it is not even close. The O2 is a fantastic little amp, it makes my D7ks sing, but it does not do the HE-400 any justice to my ears.

The O2 "doesn't do the HE-400s" justice. Can you please elaborate? This is by far the possibly best inexpensive, high power match to the HE-400 so far that I can find. Using the same calculation used in my other post, (.5 Ohm output resistance), a 50 Ohm load should get approx 960 mWs from an O2 (beating the Schiit by virtue of lower output impedance only). This assumption may or may not hold for other factors.
 
I am mostly interested in loudness provided by your O2. if you think the sound quality is poor, elaborate, but treat it as a separate issue.

 

[MattTCG]

Quote:

I usually listen to my Asgard at like 30-40% for extended listening sessions. Rarely go up to 50% for sessions longer than an albums worth. Tons of headroom with it.
 
Although for certain recordings, especially non-soundboard live recordings, I bring it up about half way, maybe a little more.
 
EDIT: At least if I'm remembering correctly. I put it sideways so it's hard to tell...

 
I wish that Schitt would have added the white indicator light to the volume pot, so that I could see just where I'm at with. I guess it's classy to have just an indention on the knob, but I might try to add at dot of paint just to see if it stands out a little better. I can always remove it. 

 

[RUMAY408]

Quote:

Using the power of math (thanks to other members), I have a rough idea of a few amps:
 
TI TPA6120A2 chip (found in some high end sound cards, 10 Ohm output):

Impedance	Output
16	1,160 mW
32	890 mW
50	120 mW
600	79 mW

Schiit Asgard (1 Ohm output):

Impedance	Output
16	2,710 mW
32	1,440 mW
50	942 mW
600	81 mW

Audioengine D1 (10 ohm output):

Impedance	Output
32	72.3 mW
50	55.7 mW
600	6.5 mW

 
Perhaps as expected, higher output impedance has a huge impact on power output as the headphone impedance goes up. At 50 Ohms, even a good performer like the TI has fallen on its face in terms of reaching our 500 mW level. Notice that the Asgard maintains big power through 50 Ohms, but at 600 would be down to an estimated 81 mW. First key spec then is a minimum output impedance! Unfortunately, I haven't found a combination of higher voltage / lower output impedance yet other than the Schiit and the JDS Labs O2.

I have been using a Bellari HA540 headphone amp it puts out 1000 mW @ 16 Ohms with a maximum gain of 35dB.  They retail at 299 but I bought mine for 249 and I've seen these priced as low as 219.  It uses a 12AX7 tube which I would upgrade over the Ruby stock.  I agree with all the comments that have already been given, you need more power with either the Senns 595 or the HE400's to make them really sing.

 

[MattTCG]

Quote:

The O2 "doesn't do the HE-400s" justice. Can you please elaborate? This is by far the possibly best inexpensive, high power match to the HE-400 so far that I can find. Using the same calculation used in my other post, (.5 Ohm output resistance), a 50 Ohm load should get approx 960 mWs from an O2 (beating the Schiit by virtue of lower output impedance only). This assumption may or may not hold for other factors.
 
I am mostly interested in loudness provided by your O2. if you think the sound quality is poor, elaborate, but treat it as a separate issue.

 
I tried the o2 with the he400 and didn't like it at all. It was clean and had plenty of volume, but it just sounded strange. The sound was no longer that enjoyable. Sub bass was a good bit leaner to me and it was brighter in the treble. 

 

[Fearless1]

Quote:

The O2 "doesn't do the HE-400s" justice. Can you please elaborate? This is by far the possibly best inexpensive, high power match to the HE-400 so far that I can find. Using the same calculation used in my other post, (.5 Ohm output resistance), a 50 Ohm load should get approx 960 mWs from an O2 (beating the Schiit by virtue of lower output impedance only). This assumption may or may not hold for other factors.
 
I am mostly interested in loudness provided by your O2. if you think the sound quality is poor, elaborate, but treat it as a separate issue.

It lacks dynamics and body to my ears at low volume and high volume. One can only give opinions on here, my opinion is I do not like it one bit with the HE-400. I love it with the D7ks and some of my other cans.