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I don't think there is anything to gain from adding an external headphone amplifier. The HPA-2 in the DAC1 is our top-of-the-line, studio reference quality headphone amp.
Hi Elias,
I'm curious, does the HPA-2 drive the balanced outputs of the DAC1 as well? I've been hearing for ages that the HD650 scales extremely well with balanced operation, and having a reference-grade USB DAC with true balanced outputs and a high quality inbuilt balanced amplifier all in one unit would be very attractive.
Also, is the HPA-2 a discrete circuit, or opamp based? Just asking because I'm not familiar with the HPA-2 at all.
I'm curious, does the HPA-2 drive the balanced outputs of the DAC1 as well? I've been hearing for ages that the HD650 scales extremely well with balanced operation, and having a reference-grade USB DAC with true balanced outputs and a high quality inbuilt balanced amplifier all in one unit would be very attractive.
Also, is the HPA-2 a discrete circuit, or opamp based? Just asking because I'm not familiar with the HPA-2 at all.
Those questions were answered earlier in the thread. The headphone and line output sections are different, the DAC1 is not designed to drive headphones out of the balanced outputs (and Elias recommends against it), and the headphone section uses either a NE5532 (regular DAC1) or a LM4562 (DAC1 USB and DAC1 PRE) op-amp for the headphone section. At least, that's what I remember.
...does the HPA-2 drive the balanced outputs of the DAC1 as well?
No, the HPA-2 drives the headphone output only.
Originally Posted by Covenant
I've been hearing for ages that the HD650 scales extremely well with balanced operation, and having a reference-grade USB DAC with true balanced outputs and a high quality inbuilt balanced amplifier all in one unit would be very attractive.
The DAC1/USB/PRE does, in fact, have true-balanced outputs. These outputs can drive balanced headphones. However, I strongly advise against this configuration using any balanced headphone amplifier.
I've written about this here and many other places, but I'll quickly summerize for you.
Balanced headphone have many inherent drawbacks, and very little substantial benefits.
Inherent drawbacks include:
- Double output impedance
- 50% reduction of damping factor
- 100% increase in noise
- +/-200% increase in distortion.
Benefits include:
- Increase gain
- Increase slew rate
These 'benefits' (increase in gain and slew rate) are hardly worth the major drawbacks. The gain and slew rate of the Benchmark's HPA-2 are far more then they need to be for the application, so increasing them won't gain any performance increase.
Originally Posted by Covenant
Also, is the HPA-2 a discrete circuit, or opamp based? Just asking because I'm not familiar with the HPA-2 at all.
I've addressed this here, but I'll recap for you. The output driver of the HPA-2 is the BUF634, a high-speed buffer amplifier capable of 250 mA output current and 2000 V/uS slew rate.
Thank you very much for your prompt response, Mr Elias. Its great to see you're still active here and so knowledgeable about your product, I wish more manufacturers would aspire to such support. You're a gentleman and a scholar
I wont pretend to fully understand the link you provided listing the technical reasoning against balanced operation, however this seems to fly in the face of conventional wisdom on these boards. Its been drilled into us like a religious sermon that balanced operation will always exceed unbalanced operation in terms of extrating the last ounces of sound quality from a headphone, especially with the Sennheisers.
The reason touted is normally the elimination of crosstalk and the doubled voltage swing provided to each driver - the Senns are reputedly very voltage-swing dependant, and subjective listening tests seem to have verified this.
I'm not disputing your information, however i'm just curious as to why oppinions are differing so much on this. Even if the balanced line-out stage of the DAC1 USB was somewhat inferior to the headphone amp for the purpose of driving headphones, I would have wagered that a balanced HD650 would still far outperform an unbalanced HD650 with the DAC1 USB as source/amp.
Benchmark Dac1 plugged into belkin or monster surge protector with power filter
Hi guys! I am planning to buy benchmark DAC1 USB. I have sometimes the hum problem when I am listening to music with my headphones through headphone output of my onkyo integrated amplifier. I guess I have a ground problem.
Does Benchmark DAC1 suffer from hum problems as well? I will use DAC1 only plugged to my laptop purely for headphone listening. Only DAC1 and laptop will be plugged into the same strip. Also about those surge protectors with power filters(not the big powercenter models in a box), how do they behave with DAC1? I will either buy a monster HTS1000 or belkin pureav surge protector. I heard that they generally improve video quality of plasma TVs etc but that some amplifier really do not like them. Will they improve or decrease sound quality of DAC1 USB?
*blank stare* I am confused Someone mentioned above that they use different opamps - I thought the head amp might have been upgraded a little at the same time as the addition of the USB.
Does that mean that if I don't need USB, I can buy an ordinary DAC1 and it'll be otherwise identical?
Someone mentioned above that they use different opamps - I thought the head amp might have been upgraded a little at the same time as the addition of the USB.
Linear Mode
