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Need amp for DT990 (need help)

post #1 of 7
Thread Starter 



i recently bought a pair of dt990 250 ohm after coming for various IEM's and need help choosing a suitable amp as i really have no clue what i'm looking for. I have had a few portable amps and currently have a total bithead i used to use with my IE8 and it obviously isn't doing the DT990's any favours at all. My budget is about £150 max so what should i be looking at? These are what i have seen that are easily available at an affordable price.


Fiio E9

Little dot mki+

Hifiman EF2A


can any of these run the 990's, which is best or should i be looking elsewhere.


Any help would be much appreciated.

post #2 of 7

I find the Bithead does a good job at driving my DT990's ( 250 Ohms ).


Make sure you do two things when using this combo.  Turn the volume of the mp3 player/source going into the Bithead to full, switch the Bithead to High Gain, and leave the crossfade off.  Just lower the volume on the Bithead to zero before you plug in your headphones and increase the volume to pleasurable levels.  I did extensive testing with my Bithead plus DT990's and found the combo quite nice.


I will do some more listening with my Bithead / DT990 combo tonight to make sure I am not missing something, but it worked great the first time I tried it a few weeks ago.


Are you sure you have a 250 Ohm DT990 and not the 600 Ohm version?

My Bithead + DT990 Portable Setup

iPod Touch at full volume with not EQ settings  -->  via mini to mini -->  Bithead on High Gain plugged into a USB port on my PC, my DT990's into the left headphone out of the Bithead.


Could you explain your audio train a bit so we can help catch any problems you may be having?  Are you using battery or USB to power your Bithead?  Are you using the DAC of the Bithead?

post #3 of 7
Thread Starter 

I've been using it like you suggest, but it just seems a bit thin sounding and a little too quiet for me. I've been using it from my ipod nano lod and from my laptop via the usb and suprisingly it sounds a bit better from the laptop. I put in brand new batteries so that can't be an issue, but i get the clipping light flashing at just over halfway volume on the bithead, which is too quiet to feel the weight of the music. As to wether they are definately 250 ohm i'm not sure as i got them on the trade forums and was told they were 250 but is there a way to know for sure?

post #4 of 7

Be sure to check your iPod nano for volume limiting.  I found several people set this and forget that it is on.  If you remove volume limiting you can get much higher volumes which will increase the gain into the amp.  I think when I ran my ipod into my Bithead I had the volume on the Bithead at say 40% at most and it never clips.


You can check the impedance of a headphone or speaker by using a volt meter that has an impedance setting usually denoted by an Ohm symbol.  Simply measure between the very tip and the back most part of the sleave, not the sleave between the two black lines.


If I had to guess I would say your nano has volume limiting on which is the most common problem with the symptoms you describe.


I will grab my nano this weekend and do some more testing.

post #5 of 7

Check in the plug there it should have engraved the correct Ohm value... 

post #6 of 7

There is no engraving on my DT990's.  I just measured mine with a DVM and they are 256 Ohms.


Originally Posted by paconavarro View Post

Check in the plug there it should have engraved the correct Ohm value... 


post #7 of 7

I finally did a test with the Bithead ( running on batteries ) driven by my nano powering my DT990's ( 250 Ohms ) and frankly the amp does improve the output, but not by much.  I heard a little more air and definite quickness to the highs, but the low end really did not improve at all.  Things become a little more spread out which was nice, but there is room for improvement for sure.


With everything setup correctly on the nano the amp can drive the DT990's easily.  I kept the volume within the first 3rd of the volume wheel.


To me it looks like the Fii0 E9 gives the greatest output power ( 1W at 16 Ohms ) and actually lists the use of up to 600 Ohm impedance headphones.  I would try it out and see if you like it.  The numbers look pretty good for the price point.

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