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Which of these is a Grace Design m903 a goof match for?

post #1 of 26
Thread Starter 
Hi,

I have this DAC/amp ( Grace m903) and I use it to power AKG K 702s. Despite being 62 ohm cans, i need to run he amp at 80% volume to pwer these. It has an output impedance of 1.2 ohms and puts out 1200 mW @ 50 ohms, 240 mW @ 250 ohms and 100 mW @ 600 ohms. I use the balanced TRS outputs for my active monitors ( Neumann KH120s) so I will be using the headphone outputs. as a point of reference I have AKGs for listening around the house and Westone 4Rs for when I travel.

I am considering upgrading my headphones and I am considering a number of the "usual suspects".

Audeze LCD-2 are 60 ohms
Beyerdynamic Tesla T1 are 600 ohms
Denon AH-D7100 are 25 ohms
HiFiman HE-500 are 38 ohms
Sennheiser HD800 are 300 ohms

All of these are well liked are any a better match with my amp? Also, in terms of a jazz listener seeking greater musical detail, soundstage and imaging which would you recommend?

Thanks,

Bob
Edited by iim7V7IM7 - 7/31/12 at 2:27pm
post #2 of 26

I have tested the following headphones with the m903:

 

Audeze LCD-2 are 60 ohms
Beyerdynamic Tesla T1 are 600 ohms
Denon AH-D7100 are 25 ohms
HiFiman HE-500 are 38 ohms
Sennheiser HD800 are 300 ohms

 

To my ears the Denon and HiFiman sounded the best.  The m903 is a tad lean in the bass so having a slightly bass heavy headphones helps make the sound more neutral.  I personally use the AH-D2000 with my m903 and the only headphones that I would consider using over it would be the HE-500, but at x3 the cost I just could not justify the expense.

 

The Audeze LCD-2 Rev 2 sound more neutral than the HE-500 and have a little more treble.

 

The Denon AH-D7100 will probably sound very similar to the D2000, but without having the charts at hand I am postulating that result.

 

The HD800, as expected, was quite power hungry and I end up at volume setting 76 to achieve the sound I want out of the HD800.  At that loudness my ears would fatigue after 10 minutes of listening.  I think that is an issue with the HD800 in general and the only way I would ever end up with a pair of HD800s would be if I were to go fully balanced including amp, DAC, and headphones.

 

The HE-500 and m903 create quite a synergy and that combination would be my highest recommendation.  If you do not already own a pair and can pick some up the AH-D2000 would be a less expensive option.

 

The HE-500 needed 1 inch of extra padding on the top of the headband to be properly positioned.  If you end up with that combo you may want to play around with the fit and headband location prior to making a conclusion.

 

For Jazz you are going to want something with some treble because of the cymbals and the airy nuances that can be found in many great Jazz albums.  The LCD-2 Rev 2 does quite well here, but with all of the driver issues Audeze is having I would shy away from the LCD products for now.  I have heard at least two sets of LCD-3s with veils, the flat ribbon cable is hardly shielded, and there have been reports with cracking on the wood earcups.  That all combined makes me shy away from the LCD products, but the LCD-2 Rev 2 is my favorite sounding and build quality of the headphones Audeze offers.

 

I did listen to the T1 through a Peak Volcano hybrid amp a while back and I found the same issue with that setup as I did with the HD800.  To achieve adequate instrument separation the volume had to be way too loud causing ear fatigue.  The T1 sounded a tad dry to my ears and lacked musical life that Jazz requires.

post #3 of 26
Thread Starter 
Thanks...

I did not realize that Audeze's was still struggling with driver related quality challenges. Thanks for sharing your impressions with the m903. I suspected that driving the Beyerdynamics or Sennheisers might be tough for my amp to drive. That leaves the LCD-2s, AH-D7100s and HE-500s.

The Audeze's bring concerns on weight/comfort and QC concerns

The Denon's are unknown at this point because of their newness and I am not sure about a closed design.

The HiFimans bring concerns about weight/comfort

Thanks,

Bob
post #4 of 26

The HE-500 I tried were much lighter and more comfortable than the LCD-2 and LCD-3.  The only gripe is not having a 1/2 inch thicker headband, but that is easily remedied.
 

post #5 of 26
Thread Starter 
The Audeze are 570g and the HiFiMAN are 502 g. Both are > 2x as heavy as my AKGs. The Sennheisers, Denon's and the Beyerdynamics are in between he K702s and the Audeze and HiFiMAN.

I am a bit surprised that people feel that the 300 ohm Sennheisers might requir more than my amp can output. I thought that approx. 200 mW @ 300 ohms would have been adequate to power them.

I will be curious to hear what people think about the new Denon's.
post #6 of 26
Quote:
Originally Posted by iim7V7IM7 View Post

The Audeze are 570g and the HiFiMAN are 502 g. Both are > 2x as heavy as my AKGs. The Sennheisers, Denon's and the Beyerdynamics are in between he K702s and the Audeze and HiFiMAN.
I am a bit surprised that people feel that the 300 ohm Sennheisers might requir more than my amp can output. I thought that approx. 200 mW @ 300 ohms would have been adequate to power them.
I will be curious to hear what people think about the new Denon's.

Impedance does not correlate to "easy to drive" - you need sensitivity for the other half of the equation. Relative position on the volume control also doesn't tell you anything. http://audiokarma.org/forums/showthread.php?t=58829

200 mW is enough to blow your head off with any of the headphones you've mentioned, including the 702 (it'll blow them up too!).

What are you feeding into the 903? And does that have a variable level? I think something is wrong if you need the level cranked up like that for the 702 (they are not that insensitive, not by a mile).
post #7 of 26
Thread Starter 
Quote:
Originally Posted by obobskivich View Post

Impedance does not correlate to "easy to drive" - you need sensitivity for the other half of the equation. Relative position on the volume control also doesn't tell you anything. http://audiokarma.org/forums/showthread.php?t=58829
200 mW is enough to blow your head off with any of the headphones you've mentioned, including the 702 (it'll blow them up too!).
What are you feeding into the 903? And does that have a variable level? I think something is wrong if you need the level cranked up like that for the 702 (they are not that insensitive, not by a mile).

The m903 is hooked to my iMac by a USB cable. To play my AKG K 702s I usually have the volume set between 75-80 out of 100. My active monitors are set between 50-65% to play at a similar volume.
Edited by iim7V7IM7 - 8/1/12 at 7:10pm
post #8 of 26
Quote:
Originally Posted by iim7V7IM7 View Post

The m903 is hooked to my iMac by a USB cable. To play my AKG K 702s I usually have the volume set between 75-80 out of 100. My active monitors are set between 50-65% to play at a similar volume.

What is the volume level set on the PC or in your media player?
post #9 of 26
Thread Starter 
Output volume is at 75%
post #10 of 26
Quote:
Originally Posted by iim7V7IM7 View Post

Output volume is at 75%

Set the software volume to 100 and control the volume on the Grace.
post #11 of 26

As far as I can tell, needing to turn the volume on the grace up to around 70-80 for normal listening levels is by design. Don't worry about it, it does not mean that your amp cannot drive headphones well, it just means that Grace set the parameters for their volume scale a bit different than you are used to. Don't forget that you can set an (up to) 9.5dB boost in the menu, and you can set the default volume for the device when it powers on so you don't need to scroll all the way to 70+.

post #12 of 26
Quote:
Originally Posted by Jeff Graw View Post

As far as I can tell, needing to turn the volume on the grace up to around 70-80 for normal listening levels is by design. Don't worry about it, it does not mean that your amp cannot drive headphones well, it just means that Grace set the parameters for their volume scale a bit different than you are used to. Don't forget that you can set an (up to) 9.5dB boost in the menu, and you can set the default volume for the device when it powers on so you don't need to scroll all the way to 70+.


+1. I have the boost set at +9.5 on my unit and listen at 70-75 on my T1's. Anything above 75 is already pretty loud.

post #13 of 26

You want to volume input from your PC as close to if not at 100%.  This prevents the amp from clipping early.  I run Foobar2000 set to 100% volume and typically have my Grace m903 at +57dB for my Denon AH-D2000.  I do use a +5 dB boost so the volume is actually at +63dB.  Running it at 70-80 sounds a bit high especially for the AKG K701 or AKG Q701.  You are making your amp work even harder by having its volume high and the PC volume low.  Of course 70-80 is in the acceptable range, but even the Grace boys would say that is a bit high for the AKG K701 headphones.

post #14 of 26
Thread Starter 
As a point of reference, my Westone 4Rs are at a similar volume to the AKGs set at 80 % with the Grace set at 60%. I will raise the output volume.
post #15 of 26
Quote:
Originally Posted by iim7V7IM7 View Post

As a point of reference, my Westone 4Rs are at a similar volume to the AKGs set at 80 % with the Grace set at 60%. I will raise the output volume.

Again, it's relative. All you're really comparing is sensitivity with this statement, and the 4R are more sensitive.
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