[superjawes]

That output impedance seems crazy high...

At any rate, there are two benefits to getting a dedicated headphone amp (IMO and at least two). First: noise. Many headphones are going to be more sensitive compared to their speaker counterparts, which means that more noise can and will be passed right through. On top of that, a speaker sits in a room, so as long as the amplifier noise level is lower than ambient noise, it won't be heard. Headphones, being right next to the ears, don't have the same luxury when it comes to amp noise. Someone designing a headphone amp knows all of this this and can be meticulous about designing a very low noise floor.

Second: other headphones. It is really, really easy to switch out transducers when they can be mounted on your head, so if you have a pair that can benefit from an amp (like the HE-400i), you're also making an invesment in potential future purchases.

In this particular case, if the HE-400i sounds good, then the only reason to get a dedicated amp is for potential future 'phones. You might get a small SQ increase, but I wouldn't make any promises. If you want a basic suggestion, a Schiit Magni 2 should do nicely, it can be paired with a Modi 2 (or Modi optical), and you can always "splurge" on the Uber versions for a small premium.

 

[cel4145]

That output impedance seems crazy high...

Yamaha has something similar going on with their headphone amp ratings: http://www.head-fi.org/t/768188/unmasking-headphone-jack-specs-from-yamaha-receivers

At any rate, there are two benefits to getting a dedicated headphone amp (IMO and at least two). First: noise. Many headphones are going to be more sensitive compared to their speaker counterparts, which means that more noise can and will be passed right through.

I don't think the answer is quite that simple. A speaker amp headphone jack could have as low a noise floor as a headphone amp. Really depends on the speaker amp and the headphone amp being compared.

 

[superjawes]

I don't think the answer is quite that simple. A speaker amp headphone jack could have as low a noise floor as a headphone amp. Really depends on the speaker amp and the headphone amp being compared.

Well yes. It also depends on what the jack is being connected to in the amp circuit. Still, I mainly wanted to point out that designing a speaker amp has different requirements than designing a headphone amp, and it could make a difference to the end result. Speaking as an engineer, if a more expensive component isn't going to give me an increase in performance, I'll stick with the cheaper part.

But again, yes. We can't over-generalize components. Heck, the headphones you want to use are going to make a huge difference. The noise floor is much more relevant to uber-sensitive IEMs than it is full-size, high impedance cans.

 

[cel4145]

Well yes. It also depends on what the jack is being connected to in the amp circuit. Still, I mainly wanted to point out that designing a speaker amp has different requirements than designing a headphone amp, and it could make a difference to the end result.

No doubt. But people sure do love their speaker tap setups with HiFiMan headphones and speaker amps. Might be the best way for him to go

 

[kdejonge]

Great guys, thanks. I am learning a lot here . I am also reading several other threads that suggest that the pre-out might not pose a problem or even issues with the sound, that at least would solve the impedance issue. 
 
I'll start with listening more to the HE-400i on my amp as I haven't done that a lot before making any rash decisions  Then ill probably listen to someones amp at a meet to compare .
 
again thanks all!

 

[PurpleAngel]

  Great guys, thanks. I am learning a lot here . I am also reading several other threads that suggest that the pre-out might not pose a problem or even issues with the sound, that at least would solve the impedance issue. 
 
I'll start with listening more to the HE-400i on my amp as I haven't done that a lot before making any rash decisions  Then ill probably listen to someones amp at a meet to compare .
 
again thanks all!

What sources do you get your audio from, for the RA-12?

 

[kdejonge]

  What sources do you get your audio from, for the RA-12?

I have a turntable on phono-in, sacd player on cd-in and raspberry pi on optical-in to play flac/spotify. I mostly plan to use the optical and sacd player for the headphone.

 

[cel4145]

I think your best bet, then, is to use the pre-amp out to hook to a headphone amp and see if helps.

Now the HE-400i are low impedance, low sensitivity headphones. So they are a bit difficult to drive, and you probably want a solid state amp (many tube amps are not ideal for that). Even something like a Schiit Magni 2 would make a difference *if* the impedance load of your amp is affecting the HE-400i performance.

 

[kdejonge]

Another option would be to use the HiFiBerry (burrbrown https://www.hifiberry.com/dacplus/) dac I have for my raspberry pi and then use two splitters, one for the sacd and one for the raspberry. One set goes into the amp and one set into a RCA selector into the headphone amp...

 

[thefiend1]

I know this is a 2 year old thread but I just ordered the RA-12 and im curious what the OP ended up doing.

I dont really have heavy to drive headphones but I do plan on using this with headphones quite a bit. I'll be using playing music from iTunes (on my PC) through a TosLink cable connected to the RA-12.

 

[ProtegeManiac]

I know this is a 2 year old thread but I just ordered the RA-12 and im curious what the OP ended up doing.

I dont really have heavy to drive headphones but I do plan on using this with headphones quite a bit. I'll be using playing music from iTunes (on my PC) through a TosLink cable connected to the RA-12.

If you use a headphone with impedance at 150ohms or higher it should be fine. Sensitivity is high enough on almost all of these anyway. If you're using the RA12 to drive speakers primarily then this is the easiest way to integrate a headphone into the system.

 

[thefiend1]

Did you mean 150 ohms or lower? I’m confused. I thought the lower it is the easier to drive. I’m going to powering a pair of B&W bookshelf speakers with the ra-12 and but more likely than not I’m going to be listening with headphones. Currently I have a pair of AKG K550 which are rated at 32 ohms I think - but may get another pair soon and would like to be safe up to 300 ohms.

 

[ProtegeManiac]

Did you mean 150 ohms or lower? I’m confused. I thought the lower it is the easier to drive.

Load impedance can affect power since it requires more voltage to produce the same power at 300ohms as at 32ohms. However there are a lot more headphones with high sensitivity and high impedance, so they don't really require the same power as low impedance, lower sensitivity headphones.

Add to that how speaker integrated amps have high output impedance. On low load impedance this results in lower damping factor so your headphones can end up sounding like they have a mudslide for the bass or like a tin can with a faint hint of a mudslide for bass in the background. On high load impedance this just boosts midrange.

Even for speakers lower impedance isn't always better. Try hooking up a 4ohm, 86dB/1watt at 1m Dynaudio to an amp that is just enough for an 8ohm, 90dB/1watt at 1m Paradigm.

 

[thefiend1]

Forgive me but I dont understand anything you just said hahaha. I need to read about this stuff because I feel like I should know at this point...

Will I be good with my AKG K550 and something like the HD660s/HD800 with my Rotel RA-12? Or am I going to need to do something different? Thanks again and I apologize for my extreme ignorance

 

[ProtegeManiac]

Forgive me but I dont understand anything you just said hahaha. I need to read about this stuff because I feel like I should know at this point...

Even the headphone output has its own impedance. If that's too high relative to the headphone, it will alter the sound because the damping factor - ie, how well it can control driver movement - will be lower. In some cases, most commonly when the output impedance is higher than the load impedance, the headphone will sound like a tin can with imprecise and weak bass. In other cases, typically when the output impedance is lower but not that low (very general rule is 1:8 ratio), it just bloats the bass, in many cases not by much. In other cases where the output impedance is high and the load impedance is also high - but the ratio is still far from 1:8 - the headphones can have a boost in midrange. This last one is why high impedance Sennheisers aren't severely handicapped on such systems and, in the case of OTL tube amps, that just adds to the tube warmth, and why people like using such amps on these. Valhalla2 isn't all that warm because for an OTL circuit it has a very low output impedance. Still high, but at least it doesn't drastically EQ high impedance cans.

Will I be good with my AKG K550 and something like the HD660s/HD800 with my Rotel RA-12? Or am I going to need to do something different?

Highly likely the HD800 and even the HD660S will not be far off from what they'd sound like driven by, say, a Magni3, but not case for the K550 since it's lower impedance.