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In search of a new AMP/DAC...

Discussion in 'Headphone Amps (full-size)' started by N0sferatu, Dec 6, 2018.
  1. N0sferatu
    I'm looking to have more punch in my headphones. Currently the setup sounds "really good" to me. It's the following:

    AMP/DAC: Audio-GD FUN
    Headphones: Sennheiser HD600 & Fostex TH-900
    Source: Computer (Spotify + FLAC Stuff)

    So, I've had this setup pretty much untouched since 2010/2011 (sans replacing a Denon D7000 with the Fostex a few years back). Recently, I upgraded my movie room with an Anthem MRX-720 (AV Receiver). One night just for fun I decided to pop the headphones into the amp. BIG MISTAKE! :o2smile:

    I couldn't believe the punch and power it could give to something even like the HD600. It drove them so easily to deafening levels with a good amount of dynamics still intact. I want that kind of kick in a headphone amp/dac. Any recommendations? I don't care if it's an amp/dac combo or if I have to purchase them separately. I need USB input though as I use it on my laptop.

    Prefer to keep it under $2,500 because at that point I could just buy another Anthem receiver. Albeit it's a waste of the unit since that's not what it's intended for. I reached out to Anthem to find out more details about the circuitry and didn't get very far. This is what they told me...

    Here's the anthem...
  2. JohnIgel
    Deftone likes this.
  3. N0sferatu
  4. ProtegeManiac Contributor
    The loudness could be just as much higher gain and the added punch could be more attributable to higher output impedance. Check with Anthem regarding the output impedance of the headphone output on the receiver. If it's anywhere above 30ohms, that's the most likely explanation for the added punch. If so, a quick way to test is by getting an OTL amp to work with the Fun (if it has a Line Out from its DAC), like a Darkvoice DV336 or Little Dot Mk2.

    Note however that this is only for higher impedance headphones, ie, there is a slight boost to the low end but the upper range is slightly rolled off but it's enough to make the boost at the low end seem louder (ie reduced auditory masking), but with lower impedance headphones, you can get weak and inarticulate bass in some cases. Plus the power delivery is biased towards high impedance, so you're going to put less power into the low impedance headphone.

    There's a Cayin transformer coupled amp though that has variable output impedance which delivers a lot of power into low impedance where lower sensitivity tends to need it. If you can spend that much go for it and just flip the switch to high impedance load mode all the time.
  5. Deftone
    Oh it really does even the CMA400i, with balanced i have never heard the same bass impact from 650s on any other amp.

    CMA400i is around 400mw bal or step it up to CMA12 for 800mw bal.
  6. N0sferatu
    I did reach out to Anthem and they were I'll just say "cute" with their response. I'll quote it below. Anthem said:

    "Glad to hear you like it! Not all that surprising though, you’ll notice when you plug in the headphone that the internal amps stop powering your speakers. That’s because the 720 is actually powering the headphones from the internal amps through a specialized conversion circuit. Unfortunately it’s not likely you’ll find this available as a headphone amp. Although maybe we should make one!"

    Since I'm debating going separate components should I maybe buy a better DAC and use the FUN as an AMP or go the other way around and buy a better AMP and use the FUN as the DAC for testing purposes? I don't want to just throw away money but after 7-8 years of being stagnant I have the bug again to give it a slight change.

    Interesting. Being in the USA, I did some Google searches of the company they're like my Audio-GD FUN. Just about zero presence in the states. I bought it back in the day since there was a state-side reseller/supporter (who I now found is out of business). That's why Schitt got my attention.
  7. ProtegeManiac Contributor
    The bad news: I don't think whoever responded has enough understanding of how amps work. Of course you won't find a speaker amp circuit routing to a headphone output on a headphone amp, the output stage is designed specifically just to go to the headphone output in front, not speaker posts in the rear; at the same time a headphone amp's design is more focused on maintaining a linear response with loads from 8ohms to 600ohms and usually in a more compact package, and given it's never meant to drive speakers several meters away, well, it's not really designed to deliver as much power (and has to fit on a desk easily outside of amps like the Mjolnir).

    The good news: at least you know it's not one of those cheap amps with a crap headphone driver stage (or not even like Marantz with one of those Philips chips that eventually made its way into the Fiio E9 and E09K), although that still leaves you with the question of whether it was merely that you were listening a lot louder but still have loads more power in reserve, or because the output impedance was boosting the low end but just managed to not cause enough driver distortion to make the bass wobbly.

    Isn't the Fun designed to be a lower cost (at the time), lower power output Class A amp with built in DAC? If you want more power (and maybe keep the amp operating in Class A) and the Fun has a line output, maybe just get a new amp. Something like a Burson Soloist. Or sell the Fun and save a bit more and get the Conductor.
  8. N0sferatu
    I know it's got an AKM AK4458 DAC in there. Just don't know the amplification it's using.

    I don't know which area is the weak point of the Audio-GD FUN. I don't know if I need a better AMP better DAC or both? That's why I was contemplating buying maybe one of the components (AMP or DAC) first and keep the FUN doing it's thing and see if anything changes.
  9. ProtegeManiac Contributor
    It might be both but it's unlikely to have a much of it on the DAC.

    If what you're hearing out of the receiver is louder and punchier, that could be a function of power quantity as much as quality. But as good as your receiver is, there's still the possibility that it's the latter, meaning high output impedance boosting the low end, making it seem more "dynamic" since you can hear the percussion pop out more. In some cases a DAC can influence that either because the DAC's response is kind of like that or you're comparing two DACs where one has a much lower voltage output, which affects overall output, and the perceived dynamics could be due to the amp not being able to compensate with enough power for the lower voltage DAC.

    Given the Fun is a desktop unit, even with DACs like the Modi and Modi2 having less than 2V on the output, that is still less likely. And at the same time since the AudioGD has a good amp design I'd much rather guess it's a lot less of the Fun being a smaller unit with 1watt at 32ohms (which is already plenty) but the resulting response due to output impedance.

    One way to try to isolate the DAC (though all this will do is confirm that what you want will come from the amp) is to use the receiver's DAC to feed an analogue signal into the Fun (if it has analogue outputs not controlled by its preamp) and then use the Fun DAC's line out into the receiver (if it has analogue inputs). I'm 99% sure it won't change a lot from what you're hearing now using each independently.

    Now if $2,500 isn't that hard for you to spend there's always the option to go with a Burson Conductor or a Soloist (and use the Fun's DAC, or buy another DAC), though on the latter and older units of the former you're going to have to use a stepped volume control. Alternately there's the WooAudio WA6se and then just look for tubes that would make the sound warmer while giving you a lot of gain (for not any more noise than the stock tubes).
  10. dw1narso
    What you possibly hear is the Anthem amplifier itself, with the power scaled by using conversion circuit. I doubt that it is hardly a specialized one and most probably would look likes this: https://diyaudioheaven.wordpress.com/tutorials/power-amp-adapter/
    Hooster likes this.
  11. Hooster
    Punch may just be a symptom of 2nd order harmonic distortion. To me bass should sound natural. If it is somehow exaggerated and perhaps "punchy" it may mean that the amp is not controlling the driver properly and you are hearing doubling due to distortion.

    Anyway, you should be able to get a similar effect by connecting your headphones to any good speaker amplifier using this method https://diyaudioheaven.wordpress.com/tutorials/power-amp-adapter/ which
    dw1narso has already kindly suggested.

    This is a hobby and experimenting is part of the fun. For example, I am currently using the RCA outs of a pre amp to drive my HD600s and I am finding that totally awesome.
  12. N0sferatu
    okay I'm going to try later in the week the following...(maybe later today if I have time)

    Isolate the FUN's DAC. DAC output to RCA input on anthem and jam away. This way I can see if the sound changes using a different DAC.

    Isolate the FUN's AMP. RCA output from receiver to LINE IN on the FUN. This way I can see using the DAC in the FUN if it changes.

    That should give me a better answer as to what I liked more out of the Anthem over the FUN correct?
    Hooster likes this.
  13. N0sferatu
    Okay with my limited testing.

    The Anthem has the juice to really kick the HD600 to another level. Using either DAC( FUN or the Anthem's AK DAC) there's subtle differences but not much. I feel there's a bit more detail in the Anthem's DAC but that can just be placebo.

    So it looks I want more amp. What can push more dynamics than the Audio-GD FUN's amp?
  14. ProtegeManiac Contributor
    Burson Soloist
  15. Hooster
    Just be careful with those dynamics. The FUN has enough dynamics to wreck your hearing before you know what is happening. Are you sure you need more of that?

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