[fjrabon]

 
tried looking through the forums for this, but can't find it. Anyone care to explain? I tried switching between the 2 modes, and haven't noticed much difference in the volume. The high powered mode may sound a little bit more bassy tho

well, yes, and no.  If you don't go above 90, you won't use the second amp tier, which is only enabled with high power mode.  High power mode doesn't make any given volume setting louder, but it does allow you to go over 90 without triggering the "OC" over-current warning.  So, in that manner of thinking, yes, unless you are going over 90, you aren't using the additional amp power that high power mode adds.  High power mode isn't a gain switch.
 
However, going into high power mode also makes the USB-computer connection become data only, which can theoretically have a few advantages.  1) it enables usage of phones as direct sources, because most phones require that no power is drawn from the device 2) it gives a more stable power supply to the DAC and amp, because typically 5V DC USB wall plugs will be more stable than USB bus power, which can temporarily fluctuate with internal power demands of the computer 4) some USB ports are noisier when they have to provide both data and power 3) some USB cables can be prone to some inner cable interference when both data and power are being drawn through the same cable (though this doesn't seem to be an issue with the monoprice cables Grace provides, it is at least a theoretical concern).
 
The high powered mode sounding more bassy is probably just confirmation bias, as none of the above factors should do anything to the frequency response.  It's possible, though unlikely, that your USB port is adding a bit of interference when it's sending power that is later converted to high frequency noise, which could be perceived as "having less bass."  The problem with these comparisons is that there's no definitive answer, as the differences largely depend on the upstream gear (cables and computer), as internally the m9XX behaves virtually identically in high and low power mode when volume is 90 and below.  

 

[fjrabon]

   
I just bought a unit second-hand but, looking at the output ratings on Massdrop page, it seems that the biggest difference you will notice will come from the use of low impedance headphones. The higher impedance headphones you use, the less margin of difference the two power levels have. I have only about 2 hours of usage on mine and have not tried the high power level, but I am using 250 Ohm and 320 Ohm headphones so I am not expecting a huge difference in power/drive. I think the main difference will be that if you are using USB for the audio signal that you might have a little cleaner power coming in when in high-power mode.

the impedance really doesn't have a whole lot to do with if you'll notice it being in high or lower power mode, it ultimately boils down to the sensitivity more.  As you noticed, the high power mode doesn't add a whole lot of power at high impedances.  But on the flip side, most low impedance headphones are also fairly sensitive, and thus you won't go over 90 usually anyway, in which case you wouldn't even be using the second amp stage, it would literally be turned off internally until you go over 90.  The m9XX wouldn't be a go-to rec for high impedance, low efficiency headphones, for the reasons you noted.  It just wouldn't have enough juice up top.  That being said, most high impedance cans are fairly sensitive, and don't require much more than 50-100mW anyway (depending on how loudly you listen).  
 
However, on some high impedance cans, you might find yourself in that 90.5-99.5 range, in which case you would notice the high power mode, in that without it, you'd keep hitting the "OC" shutoff.  It all comes down to how loudly you listen ultimately.  
 
The m9XX is a good example of proof that extra headroom doesn't equate to "extra oomph" unless it's being used. 

 

[Magick Man]

The only cans I have that go >90 are my HE-6s.

 

[fjrabon]

The only cans I have that go >90 are my HE-6s.

how do you feel about the HE-6 with the m9XX?  I've always assumed it wasn't enough power, but I have never seen anybody actually say "this isn't enough power."

 

[MonkCanatella]

I was wondering if anybody's heard the he audio jade through this amp. I can't find much info or impressions of the jade so I haven't found any pairings of these two

 

[fjrabon]

I was wondering if anybody's heard the he audio jade through this amp. I can't find much info or impressions of the jade so I haven't found any pairings of these two

isn't the Jade an electrostatic headphone that requires an electrostatic amp?

 

[Solarium]

 
well, yes, and no.  If you don't go above 90, you won't use the second amp tier, which is only enabled with high power mode.  High power mode doesn't make any given volume setting louder, but it does allow you to go over 90 without triggering the "OC" over-current warning.  So, in that manner of thinking, yes, unless you are going over 90, you aren't using the additional amp power that high power mode adds.  High power mode isn't a gain switch.
 
However, going into high power mode also makes the USB-computer connection become data only, which can theoretically have a few advantages.  1) it enables usage of phones as direct sources, because most phones require that no power is drawn from the device 2) it gives a more stable power supply to the DAC and amp, because typically 5V DC USB wall plugs will be more stable than USB bus power, which can temporarily fluctuate with internal power demands of the computer 4) some USB ports are noisier when they have to provide both data and power 3) some USB cables can be prone to some inner cable interference when both data and power are being drawn through the same cable (though this doesn't seem to be an issue with the monoprice cables Grace provides, it is at least a theoretical concern).
 
The high powered mode sounding more bassy is probably just confirmation bias, as none of the above factors should do anything to the frequency response.  It's possible, though unlikely, that your USB port is adding a bit of interference when it's sending power that is later converted to high frequency noise, which could be perceived as "having less bass."  The problem with these comparisons is that there's no definitive answer, as the differences largely depend on the upstream gear (cables and computer), as internally the m9XX behaves virtually identically in high and low power mode when volume is 90 and below.  

Nice explanation bro! I read that we can just leave our m9XX plugged in all the time somewhere on the forums so I might just do that. I turned the dimmer on so just the dot shows. Although there's this one time I left it on for 2 days and when I turned on my computer on again I had to reset the m9xx to get the sound out again.
 
By the way, I already noticed some 2 loose particles underneath the glass in front of the display, is this a normal thing? Just worried that it might drive the resell value down. Worth sending the m9xx back for?

 

[Magick Man]

The only cans I have that go >90 are my HE-6s.

how do you feel about the HE-6 with the m9XX?  I've always assumed it wasn't enough power, but I have never seen anybody actually say "this isn't enough power."

At 95-97 it works like a champ, but I can tell the amp is straining and they're pushing it hard to keep up, so the bottom-end suffers slightly. It's entirely enjoyable, though.

However, using them all the time on it could maybe shorten its life, it gets really warm. Usually I power them with a Master 9 or ECBA, they're much better suited to cope with the beast.

 

[NeoWilson]

When switching between u1 and u2 with my headphones plugged in (music not playing) i can hear my headphone making a sound similar to the sound when one disconnect headphones while music is playing. Should i be worried, whats the proper way to unplug headphones and also switching between u1 and u2 ( paused music and return the db level to 0 but still hear the noise)? Thanks
 
Also there were some discussion here about the db level everyone is using ?

 

[Solarium]

  When switching between u1 and u2 with my headphones plugged in (music not playing) i can hear my headphone making a sound similar to the sound when one disconnect headphones while music is playing. Should i be worried, whats the proper way to unplug headphones and also switching between u1 and u2 ( paused music and return the db level to 0 but still hear the noise)? Thanks
 
Also there were some discussion here about the db level everyone is using ?

I agree we should compare listening levels.
 
I use my HD800 typically at 70-72, >75 gets pretty loud and I can't tolerate it for more than 10 minutes.
 
My T1 runs from 75-77, I hardly ever go past 80 as it gets too loud as well.
 
I also tried my HD700 on it, it seems 62-65 is a comfortable level for it.
 
At no point I ever feel like I would need more power to drive what headphone I'm using now.

 

[Hansotek]

I was wondering if anybody's heard the he audio jade through this amp. I can't find much info or impressions of the jade so I haven't found any pairings of these two

isn't the Jade an electrostatic headphone that requires an electrostatic amp?

 
Yes. The Jade is most definitely electrostatic. So no, the M9XX won't power it. 

 

[lvince95]

 
I agree we should compare listening levels.
 
I use my HD800 typically at 70-72, >75 gets pretty loud and I can't tolerate it for more than 10 minutes.
 
My T1 runs from 75-77, I hardly ever go past 80 as it gets too loud as well.
 
I also tried my HD700 on it, it seems 62-65 is a comfortable level for it.
 
At no point I ever feel like I would need more power to drive what headphone I'm using now.

My TH900 only needs ~60-65 while my ZMF Omni needs like 77-82

 

[Ormia]

my he560 sounds great at 80 for classical music.

 

[kenman345]

I pre-ordered the Light Harmonic Revive figuring it would make me feel better to at least get the benefit of a purpose built unit that will make sure my USB power is clean before it hits the M9XX.
 
I will report back once I get it and have tried it out for a bit. Should ship in 3 weeks time.

 

[NeoWilson]

Hi guys, what is the fastest way to switch between m9xx and computer speaker via motherboard audio line out?
 
can i actually use jriver to play music via U2 to m9xx while other sounds to speaker at the same time?