I received a response to my email last night from John Delmo of Burson Audio.
[size=12pt]Hi Dan,
Thank you for your email and your interest in our HA-160 / HA-160D.
I will try to address all your concerns below, but if I have missed any, please feel free to write to us again. : )
1. The volume increase is constant across all 24 steps.
2. The amps provide 2 outputs, each with a different level of gain to better match the large range of headphones in the market. More volume control could be achieved by using the lower gain output.
3. The HA-160 was introduced in 2009 and we have made refinements based on customer feedback. Depending on the headphones, most customers are reporting a good range of volume control with our current type of HA-160 and HA-160D.
4. May I ask what headphone/s you are using at the moment? We can certainly customize the output gain level for you if you can send your phones to us in Australia.
5. Our decision to adopt a step attenuator over a standard pot was based on performance. Yes, a standard post is easier to use, but our step attenuator sounds better. : )
Best regards,
John Delmo[/size]
This is my follow up email responding to what John had to say, and a couple additional questions:
[size=12pt][size=small]Hi John,[/size][/size]
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[size=12pt][size=small]Your rapid response is appreciated. The headphone I presently use is the Sennheiser HD600. I have not yet had the opportunity to personally audition a Burson HA160, so my curiosity about the stepped attenuator was driven by comments to me from others who own the HA160. The comments about the HA160 were predominantly glowing, so I don’t want to leave the impression that there is any great dissatisfaction among the group of users, only that their wish list would include greater control over the lower volume levels than is presently available with the current design. Everyone supports the quality approach to volume control and low distortion through the use of your discrete stepped attenuator, with the only negative feedback centering on the lack of finer control over lower volume listening levels.[/size][/size]
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[size=12pt][size=small]I have another question. Coming off zero gain to the first stepped position, what is the decibel increase? As I understand your explanation, each subsequent step up in volume will equal this identical decibel increase through full open, is that correct? Also, you did not say whether there are any modifications available for the HA160 to help with high output at low volumes, as rumor has it.[/size][/size]
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[size=12pt][size=small]I am aware of the output level differences between the two headphone jacks based on headphone impedance. The users I have spoken with tell me that neither headphone output allows enough output level control over low listening levels to be totally satisfying to use at lower volume setting. The idea of having a customized output gain level designed to support specific headphones is an interesting offer.[/size][/size]
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[size=12pt][size=small]Finally, you mentioned refinements made to the HA160 based on customer feedback. Are you at liberty to explain what those refinements are, and how they improved the HA160 performance?[/size][/size]
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[size=12pt][size=small]Thank you for replying to my inquiries. [/size][/size]
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[size=12pt][size=small]Best regards,[/size][/size]
[size=12pt][size=small]Dan[/size][/size]
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[size=small]I thought one of the most interesting things John said was that Burson would customize the volume control for a particular headphone. Very interesting. I will post his next response when it arrives.[/size]