[CountChoculaBot]

Hi guys,
 
I'm trying to use my Cary 805C monoblocks to drive my Senn HD650s.  I'm aware I can just use a headphone cable terminated to speaker leads, but what about using this?
 
http://hifiman.com/Products/?pid=104
 
I'm aware the impedance presented by the headphones is going to be off from 8ohms by about an 1ohm or so, but I'm guessing it won't be a big deal.  I'm pretty sure everything'll be fine, but I'd just like to make sure before I drop the $$$.

 

[Scotteq]

(1) Headphone amplifiers are considered strong if they put out 2 watts, those Cary monoblocks are 50 apiece
 
(2) Senn HD 650s are 300 Ohms.  Not 8. 
 
(3) I highly doubt the headphones will be able to handle that much power, and therefore opine you're likely to fry either the Senn's voicecoils or the Cary's output stage.

 

[CountChoculaBot]

In regards to 2, it has a 10 ohm resistor in parallel.  I'm pretty certain from my research that this means the resultant resistance is then R1+R2/(R1+R2) which means my speaker amp is going to see about a 9.7ohm impedance.
 
 
In regards to 1 and 3, people run speaker amps with the Hifiman HE6 all the time, and I've heard of a few people doing it with the LCD-3, and even Denon D5000's.
 
 
Really, all I'd need is someone who's familiar with circuits in general to confirm this isn't a bad idea.

 

[Scotteq]

Yes - People do run Orthodynamic headphones - like the HE600 - off of small tube amps (usually single ended triodes) which put out a few watts.
 
HD650s are not Orthos.  Their power handling is rated at 500mw.  That is one half of one watt.   I sincerely believe that driving HD650s with a high current, 50 WPC power amp is not a good idea.  But you are, of course, entitled to do as you wish.

 

[wje]

The $99 HifiMAN adapter isn't so much of a good idea from a sound coloration level either.  I've read of a few people who have gone this route and ended up describing that the little box changed their sound output.  I would hope that such a device would remain neutral with respect to the sound, but possibly not the case in this scenario.