[Wildcatsare1]

Gentlemen, an example of excellent SS Amplifiers that have impeccable specifications, offering fully class A output, Crown and Krell. Both can be quite expensive, are very powerful, extremely well made and have excellent reputations for high performance. Hopefully, these are statements for which we can all agree.

Crown Amplifiers offer very precise, incisive, clear pictures of the music, Krell does the same, adding thunderous bass. Both very expensive, can drive and control any speaker made, both offering completely different alternatives in presentation of the music. The Crown house sound is quite similar to the O2, crystal clear, clinical, that some love, some hate. The Krell has a richer, darker tone, with greater body, also having it's advocates and those who love it's sound. Is either amp bad, colored, inaccurate, no Heaven forbid. They are different, tuned by their respective Designers too match their house sound. With the 650's, I prefer the Valhalla, with my 560's, I prefer the Lyr 2, you may have a completely different likes, dislikes, listening objective.

As TMRaven said, the O2 is an excellent amp, for those who like that "sound", but as a Crown is no less accurate than a Krell, others like different flavors of sonic truth, neither is wrong or better, just different. You love your O2's that's great, but to say that is the only sonic truth is, well, absolutely wrong.

 

[pdrm360]

Since frequency response of all headphones are not flat, the O2 cannot make them flat and uncolored, but it could be fine for headphones measurement.
The headphones frequency responses are not same, that’s why to have a better result we usually match different headphones with different amps. 

 

[James-uk]

Since frequency response of all headphones are not flat, the O2 cannot make them flat and uncolored, but it could be fine for headphones measurement.

The headphones frequency responses are not same, that’s why to have a better result we usually match different headphones with different amps. 

You do realise headphone frequency responses shouldn't be flat right?

 

[Solrighal]

This...

There's nothing out there supporting the fact that the O2 is the highest possibility in fidelity" & "but shallowly assuming it's the end-all be-all in transparency"

... is not true. What I very specifically said was this...

'The O2 is as close to "a straight wire with gain" as anyone's going to get for the money'. Oh, and I'm not shallow. At all.

 

[pdrm360]

You do realise headphone frequency responses shouldn't be flat right?

 
Just said a headphone with completely flat frequency response doesn't exist.

 

[dizzyraider]

This is a HD650 impression thread and not a Is the O2 the ultimate amp for headphones in general thread so I'm not going to argue on that point. For me, going to a more power amp has made an audible difference. I think the O2 is a spectacular amp ESPECIALLY for its price, and it may possibly be that all some one would need to get the most out of their headphones (very much DEPENDING on the headphones).
 
I don't think anyone would argue that some headphones will not get enough juice for "optimal" from the O2 (the planars for example) simply because of the power limitation. It will provide PERFECTLY  for headphones that are not as power hungry, which MANY are not. For me, I have heard an audible difference going to a more powerful amp with the HD650. It had more clarity, and a sense of better control. With the way the impedance changes with the HD650, it does make sense that it scales better with power. I think 600mw and a 1W amp may not make any difference to many headphones, but I do find the HD650 benefit form having a bit more power from the amp. Sometimes an amp that can provide more good clean power will cost more, now how much more and if it's really worth it will be up to each individual.

 

[pdrm360]

The O2 has only 150mW power for the HD650 (300 ohms) vs. Asgard 2 (380mW on 300 ohms).

 

[James-uk]

The O2 has only 150mw power for the HD650 (300 ohm). 

High impedance cans need more volts not watts . 150mw is plenty for dangerous volumes .

 

[TMRaven]

voltage is one half of wattage.  You can't have wattage without voltage.  
 
150mw is plenty of power anyways.

 

[pdrm360]

High impedance cans need more volts not watts . 150mw is plenty for dangerous volumes .

 
Volts not Amps
 
P = VI
P = power (watts)
V = voltage (volts)
I = current (amps)

 

[pdrm360]

  voltage is one half of wattage.  You can't have wattage without voltage.  
 
150mw is plenty of power anyways.

 
No it's not. 150mW = 0.15 W
 
The Magni has 260mW on 300 ohms

 

[lawrecedent]

Good to hear. Noob question, but do you need to amp to achieve that soundstage or are they good as they are.

Shoegaze is blissful, somewhat ethereal pop songs with a lot of guitar distortion and other effects way up in the mix.
https://www.youtube.com/watch?v=46XU6PGvIP4

You're welcome to tell if HD650 can contain this song well or not

I think the 650's would be able to do justice to this sort of track (slightly warm and detailed in an otherwise muddied soundstage). However, sadly the quality of Youtube audio tracks is lacking. I would never listen to any songs on Youtube through decent equipment as the quality is garbage. If you own the original recording it should work well, especially if it is a decent copy.
As regards amps, to make these headphones sound good, an amp is essential. I just plugged mine into my phone direct as a test and they were so quiet. I had to put my note 3 on full volume to really hear anything and even then the quality was poor.

 

[TMRaven]

It's plenty of power.  I always had more than enough headroom with the HD650 out of the O2.  
 
That isn't to say I thought it sounded spectacular out of O2 though.  However, more power almost never equals better sound.

 

[Solrighal]

Time for a group-hug methinks

 

[ButtUglyJeff]

Time for a group-hug methinks

 
Yes, a group hug at a head-fi meet.  Bring all our gears and let our ears decide, not specs and charts....