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Powering Sennheiser HD650's

  1. ty123
    Hello all, I am very new to the high-end end audiophile market so any help from you experienced members is greatly appreciated. My current cans are Sennheiser Momentums, which I have had for ~2 years and absolutely love. However, I've decided its time I step up my game so I've ordered a pair of Sennheiser HD650's that are supposed to arrive tomorrow. My Momentum's only have an impedance of 18ohms, but the HD650's take 300ohms. I primarily power my headphones from my Retina MacBook Pro or iPhone 6 and I've heard to get the most out of the 650's an amp is a must have. I've also read that they're notoriously hard to power, being a novice to all of this I'm sort of overwhelmed and confused. I currently own a Fiio E6 (it was like $28), which claims it can power 160-300ohms. Will these do the job or do I need to buy some more gear? Also what are DACs, and are they worth the money? If it is going to cost me another $200-300 to power these headphones I will just return them and wait. Thank you very much!
  2. ty123
    The more research I do, the more I get confused. Are amplifiers like wires? What would the benefit be in going from a $26 to $120 amp if they both can power 300 ohms. Do DACs make a noticeable difference? Also if I'm playing 320kbps bitrate, will any of this make a daference?
  3. ty123
    Still in need of any help! It seems that all of the Fioo AMP/DAC combos won't work because they're only reccomended for 16-160ohms headphones. Would buying one of these units and then a separate amp work? My headphones are arriving today so I would like to order an amp and/or DAC soon. Thanks!
  4. ProtegeManiac Contributor

    You must have come across the description of the ideal amplifier, which is "(like a) wire with gain." That's not literally like or just a wire, but that it must increase the gain without messing up the signal. Basically, all an amp should do is "amplify," not introduce (not even intentionally, as with some tube amps) any distortion to the input signal.
    An extreme example would be that a 1.2L three cylinder engine can move a 2,500lb Mitsubishi Mirage safely up and beyond freeway speeds, so theoretically, it can also move a 3,300 AWD Porsche 911 Carrera, but for some reason Porsche stubbornly sticks to large piston flat-6 engines. Why? First off, going from 0-60 in about the same time other cars like it would have already crossed the quarter mile mark will suck for the kind of money Porsche wants for that car. Second, with insufficient torque relative to the car's weight (ex. a 1199cc or roughly 1.2L twin-cylinder engine is a LOT of torque for a bike, like in a Ducati, but of course the technology in it would be more similar to what you'd find in a Ferrari or BMW M than a Mirage), you can't steer your way through corners using the throttle. In short, that 911 will drive like a 100-year old lorry with a low-slung suspension.
    Another thing to note is that that rating is a marketing blurb. There are too many other factors involved here in the same way that a 3.8litre H6 engine has more peak horsepower, more maximum torque spread over a wider range of its RPM range, a higher redline limit which can help when you're going fast through a long, fast corner (like the Km5 to Km7 section of the Nordschleife). When an amplifier increases the gain, depending on the overall circuit design (including the power supply), it will also increase the total harmonic distortion (henceforth shall be referred to as THD). Distortion comes in a variety of sounds, but the idea is it deviates from the original signal that went into it, usually as it struggles with the load that's on it - whether it's an 8ohm speaker with low efficiency or a 300ohm headphone. Let's take a run of the mill audiochip on most mainstream devices - if you can find the specs on it, it will usually have an output of 5mW at 32ohms, with 0.01% THD. Hook up a 300ohm load, and it might still make it to 5mW, but it's already at 2% THD.
    If you're not into cars or even just Gran Turismo, think of the amplifier as a digital camera sensor. Do you really need a large sensor - at the very least, an Olympus/Panasonic Four Thirds sensor or Nikon CX format sensor - to take photos when you can just get a $100 digicam? Why use an X100 or E-M5 when a camera 10% of the price of either can also take photos? Well, it depends on what you're trying to do. Since the primary thing we're talking about here is an audio amplifier, the most relevant aspect is the noise. A larger sensor with the right kind of lens can gather more light, and a good quality sensor and processor can minimize the noise in the photo, like the THD in an amplifier, especially when a flash isn't ideal (ie direct flash casts a shadow behind the subject/s). Then, much like the Porsche, these cameras are also faster - a fast shutter can freeze movement (like how sports photographers use their DSLRs), while some can focus in relatively less than ideal conditions and still take a shot before the subject is aware of it (like how people use the X100 for street photography).
    The thing with cars and cameras though is that the benefits are more easily observable. Drive the Porsche and even before you explore its handling limits you might already begin to appreciate how much better it handles than that Mirage; or you can try taking a photo of someone jumping up to dunk into the basket, and the guy who knows how to use his Canon 7D MkII and whatever lens will still give you a sharper image without any blur on it than what you can manage on a $100 camera; or no matter how much you try the $100 cam from WalMart can't get an image as sharp as and has as good a dynamic range as what someone who regularly does photos like this one gets off whatever camera he uses for the job. With audio amplifiers, not only is it hard to tell what 1% THD sounds like vs 0.001% THD, but there are less people who can immediately hear the difference. Even when they do it all gets attributed to a lot of other things, like how some systems sound "fast" while others have "somewhat sluggish bass" as purely a function of for example quality capacitors "discharging" faster when it's a matter for overall circuit design having less THD.

    They will in terms of sending a cleaner signal to the amplifier. Using an analog output out of most devices means the signal is going through whatever amplification circuit is in there, and you will either introduce a lot of distortion or you cut on the distortion by cutting the bit depth (since software volume control does it that way). For headphone systems it's not really that big of a problem choosing between a DAC and amp since many products have both in the same box, like the Ibasso D-Zero MkII. At a minimum, that's what I'd use on the HD6x0 - I have the original D-Zero and it only has a little bit of distortion vs my Meier Canatate (both have a USB DAC in them BTW).
    As for whether the differences will be appreciable, I'd say it will be in 320kbps to me. We can't answer whether you will be able to hear for example how much better the rhythm on Feist's "One Evening" or Norah Jones' "Deceptively Yours" sound like on properly driven headphones.
  5. Youth
    FiiO has some pretty good ones and they are also cheap. Heres a few that can run the HD650:
    Amp/dac: FiiO e10k (I dont know if the e17 can run the HD650 but that is also amp/dac)
    Amp: FiiO e12a. FiiO e12, FiiO E11k
    Check those out :)
  6. Me x3
    Hello there,
    A DAC is a digital to analog converter. When an USB DAC is plugged to your computer the music left the computer -via USB cable- in a digital way (01010101... you know). The DAC take the digital information and use it to create a small analog signal (a varying voltage).
    Then the amp take the small analog signal and amplifies it.
    All devices like laptops, sound cards, smartphones, ipods, have a DAC/Amp combo in there. In the vast majority of cases, those devices have very cheap DAC/Amps with regular, often noisy performance.
    (Well engineered) dedicated DAC and AMPs, or at least a good external DAC/AMP combo should provide a more transparent quality to your music.
    If you are coming from a respetable on board audio chip the differences will be subtle but noticeable. If you are coming from a noisy device, you'll find quite a big difference. It also depends on how well the music you listen to was recorded.
    If there's no transparency in the recording, a quality DAC/AMP won't give you transparency.
    HD650 are not that hard to drive, being high impedance headphones, they don't drain much current from the amp, then they are an easy load for a well engineered Amp. You only need an amp capable of giving you enough voltage to make them loud.
    Something like Fiio E10K (USB DAC/AMP) should do the trick with ease.
    There are much more expensive and refined Dac/Amps, techincally better but differences in audibility are very very subtle.
    Some other expensive gear is designed to tune the sound (DAC, Amps, Cables, etc). These devices are not designed with transparency in mind: warmish amps with tubey sound, tamed treble, etc.
    Impedance is not a measure of how hard to drive a headphone is, that's a more complex topic. Just to give you an idea, Beyerdynamic DT880 250 Ohm needs 3 times the power HD650 needs to sound at the same level.
    If there's something you don't understand, feel free to ask.
    Best Luck!
    Jimmy Gazelle likes this.
  7. ty123
    Thank you all so much! I think I've narrowed it down to 4 amp/DAC combos if you you could help me pick between them

    1. FiiO E10k - $76
    2. iBasso D-Zero MK 2 - $120
    3. iBasso D42 -$188
    4. iFi Nano iDSD - $189


    I would obviously rather spend $76 unless the more expensive ones are an obvious improvement. The main concern I have with the Fioo is that it is only reccomended for headphone with impedance 16-160ohms
  8. Youth
    That doesnt matter. The e10k will run the HD650. Check this out: http://www.audiobot9000.com/match/sennheiser/hd-650/with/fiio/e10k
    The owner of Headfonia has also said the e10k can run HD650, and they are his all-time favourite pair of headphones. Don't worry.
    It's not he optimal choice but it works. If you want better sound you have to spend more money.
  9. blse59
    If the 650's are anything like the 600's, they are easy to drive. I have the E10K and it's a great amp/dac and it works perfectly with my 600's. It's perfect for the vast majority of headphones people use, including your Momentums.
  10. Me x3

    Sennheiser HD650 is easier to drive than HD600. You need 30% more power to make HD600 sound at the same level as HD650.
  11. ty123
    Ordered the E10k w/ 1 day shipping. Can't wait
  12. blse59

    Enjoy! [​IMG] I had an E10K first. I got a HD600 over the holidays. It sounded perfectly fine to me driven by the E10K but I was insecure about whether it was enough because like you I kept hearing people say you needed a good amp to "make it sing". So I ordered an O2 amplifier which is widely considered by many to be a reference quality amp. I'm happy to report the sound out of both of these sounded the same on my HD600's.  I would argue the DAC portion of the E10K is reference quality as well. The DAC chip it uses (TI 5102) is used in many DAC's these days.
  13. deserat
    I've not run the e10k but I have run my HD600's through my Fiio x5ii, and also through and Aune T1 Mk2.  Thought they sounded great... then out of curiosity I bought an Asagard 2  and put it between Fiio and the HD600's.  Let's just say what I was hearing under the x5ii and the Aune wasn't the 600's. It was something that didn't really justify the price of the HD600. The Asgard puts out 2x the mW at 300Ohm, and I'm assuming that's what made the difference. It didn't make them lounder, it made them much clearer.  If I was going to drive Seins with an e10k... I'd go with the HD598 - which are an awesome set of cans.
  14. ProtegeManiac Contributor
    That's not because of absolute power output, but that it can output as much power as the others with less distortion, and if you can use more there's still a lot more before distortion gets in the way. Bigger (output and following that, due to power supply and cooling, size) isn't always better though - you get to a point where all the extra power will just be at hearing damage levels anyway.
  15. deserat
    That's good to know.  Key things I noticed as a difference was the sudden appearance  sound stage, bass detail, and and instrument seperation. Things I'd read about but was only able to ask, "What's that mean?" Perhaps that's just a function of volume and hearing damage I did when I was much younger.  It might be entirely possible that you can drive 300 Ohm headphone to it's potential with an amp the manufacture rates for 150. Frankly I think my 70 Ohm HD598's sound great with with the Fiio and my HD 600 sound like they are being played through tin foil. 

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