[scompton]

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Thank you for the reference to the old thread, It seems like the Pio Elite A 35 r Hp jack is made for low impedance cans. The Senn HD 280 pro ( 64Ohm) sounds smooth at not a sign of sibilance. I also tried the Sen HD 650 with the A 35R and the mid-range is just like magic. Diana krall voice in " Live in Paris" is as silky as it could be. The cymbals are crisp and the Piano sounds just right on spot. Is it what they call " moffset output stage of the A 35 R ? 
 
 

I have 2 mosfet amps and both have a nice warm sound.  From what I've read, that's typical.   Sounds like you probably won't get much improvement buying a dedicated head amp.  I have a Shiit Asgard and it's not significantly different sounding than my vintage Realistic STA-2200 that it sits next to.  It is about 10% the size though and probably draws a lot less.
 

 

[pp312]

 
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I just have to make a few comments here. First, the C352 is not vintage or anything like it. You make me feel old. Second, I was not aware the 352 has an inbuilt EQ, though it does have Bass and Treble. Third, the imbalance you experience is just poor tracking at low volumes and typical of almost every commercial amp. Fourth, I find it hard to believe that the NAD 352 sounds lean, as that would be contrary to NAD's "house" sound. However, the K701 certainly sounds lean.  
 

Sorry, might have written that post a bit poorly. I did not mean that the 352 was a vintage NAD, I was rather wondering how it was compared to actual vintage NADs. And i didn't really mean that the NAD itself sounded lean, far from it, but with the K701s it tends to. Oh and lastly, by EQ, I just i was talking about the bass and treble settings. I am sorry for making some things unclear.

Well, just try to do better next time, lad, and meantime keep a stiff upper lip, there's a good chap.
 
 

 

 

[pp312]

 
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I have 2 mosfet amps and both have a nice warm sound.  From what I've read, that's typical.   Sounds like you probably won't get much improvement buying a dedicated head amp.  I have a Shiit Asgard and it's not significantly different sounding than my vintage Realistic STA-2200 that it sits next to.  It is about 10% the size though and probably draws a lot less.
 

In my experience the decrease in power consumption is one of the main reasons for going with a dedicated HP amp. A lot of the time it's the only reason.
 

 

[scompton]

Space is another considering the size of some of the vintage monsters.  The Asgard is probably 10% of the size and weight of the Realistic receiver it sits next to.

 

[ACDOAN]

I am very curious about headphone amps that will best my Pio A 35 R intergrated amp. 
 
My choice : 1. Woo audio 3
                  
                   2. Rega Ear.
 
                   3. Matrix
 
I love tube based amp but most of my Senn will need a little hot on the treble to become alive. So I am very interested in the Rega from the price point. At this new stage in HPs, I do not want to go over $400/$500 for a headphone amp yet.
 
Any thoughts or reviews about the Rega Ear with Senn 650 please share with me. I coudnot find too much in depth about the Rega Ear.

 

[scompton]

My guess is that very few people here have experience hearing the A 35 R so you might not get much in the way of answers

 

[Skylab]

I will say that the Rega Ear is one of the worst sounding dedicated headphone amps I have ever heard.

 

[ACDOAN]

about

 
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I will say that the Rega Ear is one of the worst sounding dedicated headphone amps I have ever heard.

I also heard the same about the Creek OBH1 (?) with its HF roll-off . As they say see the forest but not the trees. I was thinking abt the Woo audio3 but there were some reviews warning about its warm sounding is a mis-match with warm sounding cans. Thanks for  feedback.

 

[pp312]

 
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I am very curious about headphone amps that will best my Pio A 35 R intergrated amp. 
 

 
Why? Has the Pioneer packed it in?

 

[ACDOAN]

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The Pioneer integrated drives my HD 650/AKG702 effortless. I never have to crank it up pass 11 o'clock without deafen myself. I am in a process of learning about the HP amps and I am exploring to see if there is better dedicated HP amp within my budget that will be better than the Pio integrated . I am looking at the Asgard,Creek, Rega, MF that falls within my budget but I wonder if they are truly an improvement over what I have or I just spin my wheels.

 

[scompton]

I just looked at a schematic for the  A 35R and it has 330 ohm, in line resistors off the speaker outs for the headphone jack.  I'd guess that you'll only see a small difference between it and a dedicated headphone amp for the HD650 unless the A35R or the dedicated amp is colored.   Impedance mismatch between the A 35R and the K702 may be coloring the sound, so you could possibly see a difference there.

 

[00940]

 
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So it is the impedance mismatch that is causing the distortion and not because of the presence of a resistor?

What if an adapter is designed in such away that the amplifier "sees" 8 ohms of impedance? It would be grossly inefficient where most power is dissipated as heat, would it in theory be beneficial for the faithfulness of the signal?

Yes, it would be beneficial for low impedance headphones, to preserve the intended frequency response of the headphones. Here is how Grado suggested to do it (not quite 8ohms but close enough), it provides a less than 2 ohms output impedance:
 

 
For higher impedance headphones, you could use a 10r-10r ratio rather than 20r-2r.

 

[ACDOAN]

Quote:

I just looked at a schematic for the  A 35R and it has 330 ohm, in line resistors off the speaker outs for the headphone jack.  I'd guess that you'll only see a small difference between it and a dedicated headphone amp for the HD650 unless the A35R or the dedicated amp is colored.   Impedance mismatch between the A 35R and the K702 may be coloring the sound, so you could possibly see a difference there.

Man, this is great info since I do not have good background in EE . Thank you .

 

[Wharfrat]

Glad to have stumbled across this thread...more goodies to hunt for.  Perhaps there is a sleeper unit or two that is of more recent make and hasn't been scoped out by the price-driving EBay crowd....vintage gear still has the looks department all sewn up....
 

 

[Hooster]

This discussion is very interesting to me. I have been on the market for a headphone amplifier but I have been severely disappointed by the lack of thought that goes into the design of most of them, even well known amps from big names. They do not seem to be meant to be integrated into a system. Some are just one input at the back and one headphone output at the front, period. Fine, if all you want is something on your desktop but if you want something that integrates into your main system it does not cut the mustard.
 
To me a headphone amplifier should have:
 
1. A headphone output. (That one is a no brainer)
 
2. Inputs for whatever you want to use it with. These should be selectable at the front of the unit.
 
3. At least one line level output.
 
4. A HIGH QUALITY volume control that tracks the channels well, even at low levels. (Not a cheap wiper pot).
 
A remote would be nice to have.
 
Ok, that is it, but note that this could in fact also be a high quality pre-amplifier! I suspect that some well respected makers deliberately limit the functionality of their headphone amplifiers because if they gave too much it would make their pre-amps redundant.
 
Finally, note that a high quality vintage receiver has the first 3 requirements and could be modified to fulfill requirement number 4.