[hauntingtheholy]

  Hello!
About your question on impedance, power ... Voltage (Vrms), I believe the link below will help you!
 
http://www.apexhifi.com/specs.html
 
On the specification of the Amp you mentioned, it generates approximately 10Vrm (9,8Vrms) with 300Ohms with 320 mW of power. More than enough to touch Sennheiser HD650.
I have a Senn hd650. In my opinion, they play wonderfully better with tubes! My suggestion (with a reasonable price) are WooAudio WA3 or Crack OTL Headphone.
 
 
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Thanks for the link.  I just scanned over it and it looks somewhat helpful.  I did download the spreadsheet they provide, very cool.  While you said the 650's can easily be touched by the Magni 2U, will they have significantly improved BASS with either a stronger amp or simply a tube amp?  
 
You said it generates 9.8Vrms 
 
I think the Woo and Bottlehead are out of my price range.  For Tube amps, I'd be looking at the DarkVoice 336 or the Schiit's Valhalla 2 or something else in the 200-350 range.  Looks like the Valhalla 2 puts out 800mW for 300Ohms.  I can't recall what DV336 has off the top of my head, but I remember thinking it wasn't more than a Magni.  Oh, and see what I did?  I just auto-mention the mW amount @ 300Ohm.  Is there any reason I need to worry about Vrms before I just buy based on the mW's?
 
 A lot of people in this thread seem to love the Asgard 2.  I wonder if that extra power will improve the bass noticeably and that's all I need?

 

[upstateguy]

  Edited
 
Quote:

  It all depends on the headamp. My HD650 can rattle in its frame when subjected to good deep bass. The HD650 needs a headamp that can manage 10Vrms on the output. Many headamps don't make the grade which results in less excursion drive for bass.

 
I have heard the 650 rattle in its frame at my friends house when plugged into a home receiver.  It had awesome bass suitable for club music.  I just got the Magni 2 Uber and it does NOT have the bass I wanted. Something I don't fully understand, though is that the headphone can get loud enough with this amp to deafen me.  In fact, I stupidly hurt my ear while cranking it too loud to hear if that would help the bass or not. The volume was at only 10'Oclock.  If I turned it up all the way, it would literally blow my eardrums out and I'd be Deaf forever.  :-O  
 
<snip>  
<snip>

 
Sounds like the receiver had the bass turned up....
 
FWIW, the bass on my 650s is relatively the same out of my  Cetron tubed Woo3 and my portable O2, the only significant difference being that the little O2 amp has much more resolution.

 

[hauntingtheholy]

   
Sounds like the receiver had the bass turned up....
 
FWIW, the bass on my 650s is relatively the same out of my  Cetron tubed Woo3 and my portable O2, the only significant difference being that the little O2 amp has much more resolution.

I do not know if the bass was up on the home amp, but I use the EQ on "rock" or "classical" setting on itunes.  That info on woo3 vs O2 is interesting/useful, though.  

 

[CptCmndrPwn]

The HD650's don't really have a good quantity of bass. I listen to mostly EDM and I sometimes even prefer my Xiaomi Pistons over the HD650s. I guess I just have a preference for bass over other aspects. 

 

[kramer5150]

The 650 is not what I would call bass-light, IMHO its got just enough bass quantity to NOT be considered flat or neutral.  IMHO of course

 

[upstateguy]

  The 650 is not what I would call bass-light, IMHO its got just enough bass quantity to NOT be considered flat or neutral.  IMHO of course

 +1 
I agree with you.

 

[nicholars]

  So I just got a pair of HD650s, the older black cover version that is suppose to be dark, veiled, and bloated bass. Everything that one could want BUT after listening the bass is on par with my old SA5000 and I don't hear that veil at all. The only sennheiser sound I can hear is that "laid back" signature. Are my amps not powerful enough? I'm using mullards in my EF2A, and the volume is at 10 o'clock, and on the D1 its the same 10 o'clock. 

 
The HD650 don't have any sub bass because they are open headphones, if you want bass get closed headphones.

 

[kramer5150]

   
The HD650 don't have any sub bass because they are open headphones, if you want bass get closed headphones.

Some planars have very deep extension, so thats not entirely true.

 

[nicholars]

  Some planars have very deep extension, so thats not entirely true.

 
Yep closed headphones or planars. Although all bassy planars except the HE400 are far more expensive than the HD650 so I did not mention them. Don't know about the mad dogs but I don't think they have a lot of bass from what I have read.