[tassardar]

Hello,

This is self reply but I have reasons. I discovered why I prefer voltage output. Recently I tested Woo Audio Dac Cable and I was shocked how good current output is. I experienced really big stage in the opposite to really close stage, stereo like without depth. Normally I use Questyle CMA 15 which has 2V on RCA output. Woo Audio Dac Cable has 1.7V so I tested preamp function in Questyle and when knob is on 100%(2V) I can observe described problems at lover volumes stage opens and sound is really holographic. Also whats strange on Sennheiser HD 800s I can notice audible noise on current output. I tested it also with other Questyle CM 15 and SMSL M400 in my local dealer with the same results. I suspect that my unit is invalid. I have sent it to Enleum service through my local dealer.

What you experience is pretty normal.

Current drive in dynamic headphone can have wild results. Also high impedence headphone on the current drive has some noise. Depending on your sensitive to it, it maybe little or a lot. I tested my library of ZMF and HD650, they have varying low level of hiss. Most of the time they are noticable unless I’m in a really quiet environment.

The way Enleum implements the volume control is also different from the rest, there they change the output gain rather then attenuating the the input. In their higher model, it’s been shown that reducing the dac volume below 2v improves sound quality in their higher model. The hpa-23rm is kinda a miniaturised Version.

 

[czervonk]

What you experience is pretty normal.

Current drive in dynamic headphone can have wild results. Also high impedence headphone on the current drive has some noise. Depending on your sensitive to it, it maybe little or a lot. I tested my library of ZMF and HD650, they have varying low level of hiss. Most of the time they are noticable unless I’m in a really quiet environment.

The way Enleum implements the volume control is also different from the rest, there they change the output gain rather then attenuating the the input. In their higher model, it’s been shown that reducing the dac volume below 2v improves sound quality in their higher model. The hpa-23rm is kinda a miniaturised Version.

Maybe to some degree it is true, but Sennheiser HD800s and DCA Expanse are unusable on current output when Dac is outputting 2V. I would understand small improvements when lowering down voltage, but simply noise is too loud on Sennheiser and sound stage on DCA Expanse is not existing. Also I used demo unit before buying mine and I didn't notice such behavior on this unit. I have read and watch many HPA-23rm reviews and no one mentioned it. For example in review from last weekend made by @WaveTheory, he mentioned that he mostly used HPA-23rm with Chord Hugo 2 on RCA outputs (please correct me when I am wrong) which are 2V and only on some IEM there was noise from current output and soundstage collapsed on this IEM. Do you think @tassardar that I should accept issue and simply change my dac to dac with lower then 2V output or to dac with really well implemented preamp? So generally pay twice for pleasure to use Enleum? I understand that many of us did it for small improvement in sound but being forced to it by real issues is another cup of tea..

 

[tassardar]

Well not asking you to accept the issue or not, just highlighting that this may just be normal operations. Quirks of the amp. The hissing is something I notice only on dynamics and not all display same volume. Similarly for the rca input it’s only when someone tested it on the Enleum higher model did I notice it.

Either way if it’s a true variant for your unit you at least get a fix.

Another thing to note is running on usb power while using the amp may have ground loop noise too unless you are powering via powerbanks

 

[czervonk]

Well not asking you to accept the issue or not, just highlighting that this may just be normal operations. Quirks of the amp. The hissing is something I notice only on dynamics and not all display same volume. Similarly for the rca input it’s only when someone tested it on the Enleum higher model did I notice it.

Either way if it’s a true variant for your unit you at least get a fix.

Another thing to note is running on usb power while using the amp may have ground loop noise too unless you are powering via powerbanks

Thanks for suggestion to check usb power. Before I have wrote post on forum I tried to check all possible, known to me, source of problems, so I tested it also without any external source of power connected. Whats a little bit sad I don't have measurement rig to confirm my findings, just my ears and whats even less reliable, my perception of soundstage. I hope that Enleum service could verify it.

 

[tassardar]

Thanks for suggestion to check usb power. Before I have wrote post on forum I tried to check all possible, known to me, source of problems, so I tested it also without any external source of power connected. Whats a little bit sad I don't have measurement rig to confirm my findings, just my ears and whats even less reliable, my perception of soundstage. I hope that Enleum service could verify it.

Do hope you get an answer. The Enleum after owning a few other portable amps can be either the best or the quirkiest amp.

 

[NehPets]

Maybe to some degree it is true, but Sennheiser HD800s and DCA Expanse are unusable on current output when Dac is outputting 2V. I would understand small improvements when lowering down voltage, but simply noise is too loud on Sennheiser and sound stage on DCA Expanse is not existing. Also I used demo unit before buying mine and I didn't notice such behavior on this unit. I have read and watch many HPA-23rm reviews and no one mentioned it. For example in review from last weekend made by @WaveTheory, he mentioned that he mostly used HPA-23rm with Chord Hugo 2 on RCA outputs (please correct me when I am wrong) which are 2V and only on some IEM there was noise from current output and soundstage collapsed on this IEM. Do you think @tassardar that I should accept issue and simply change my dac to dac with lower then 2V output or to dac with really well implemented preamp? So generally pay twice for pleasure to use Enleum? I understand that many of us did it for small improvement in sound but being forced to it by real issues is another cup of tea..

That's an interesting observation. I was a little disappointed by the Expanse, primarily due to the apparent lack of an 'expansive' soundstage, but I was using a 2V line level input. Maybe I need to revisit the Expanse, but using a lower input signal.

 

[czervonk]

That's an interesting observation. I was a little disappointed by the Expanse, primarily due to the apparent lack of an 'expansive' soundstage, but I was using a 2V line level input. Maybe I need to revisit the Expanse, but using a lower input signal.

It would nice to hear your thoughts about it, because I am really not sure if this is some design choice or some issue with my unit.

 

[czervonk]

I had a chance to test my unit and demo unit in the dealer's shop. There is a clear difference between these units on current output. It was confirmed also by store staff. As a reference demo unit is 100% of performance, then my unit on around 1.7V has about 80% of demo unit stage and less clarity. When switching to 2V the perception of stage is gone and also there is less clarity. Tested on DCA Expanse.

 

[Edric Li]

I had a chance to test my unit and demo unit in the dealer's shop. There is a clear difference between these units on current output. It was confirmed also by store staff. As a reference demo unit is 100% of performance, then my unit on around 1.7V has about 80% of demo unit stage and less clarity. When switching to 2V the perception of stage is gone and also there is less clarity. Tested on DCA Expanse.

Well that’s concerning. I thought a defective unit would sound off, not worse. How would I know if I’m listening to a 80% or a 100%… Did the voltage output sound different? Is burn-in time a factor?

 

[czervonk]

Well that’s concerning. I thought a defective unit would sound off, not worse. How would I know if I’m listening to a 80% or a 100%… Did the voltage output sound different? Is burn-in time a factor?

My amp was fully burned in. On < 2V only side by side comparison would tell which one has issue. On 2V there is clear difference because I didn’t notice any difference on demo unit between 1.7V and 2V. It is easy to notice when you have preamp. When 2V sounds bad and going down fixes it then it could be similar issue.

 

[Edric Li]

On 2V there is clear difference because I didn’t notice any difference on demo unit between 1.7V and 2V. It is easy to notice when you have preamp.

Is this the best way to check for this defect in the absence of another unit, in your opinion? Try to vary the preamp output and see if the soundstage changes.

What about the voltage output, did yours sound different from your dealer's?

 

[czervonk]

Is this the best way to check for this defect in the absence of another unit, in your opinion? Try to vary the preamp output and see if the soundstage changes.

What about the voltage output, did yours sound different from your dealer's?

As I understand when you change volume in preamp, then you change voltage output.
Let me summarise: on 1.7 V the difference is small less clarity and a little smaller soundstage. On 2V the difference is big because it is big soundstage vs no sounstage. Personally on my unit I always chose voltage over current output. I realised that something may be wrong because as most of commenters here I preferred current over voltage on demo unit. Of course current is mostly not suitable for dynamic drivers but it is another topic.

 

[NehPets]

It would nice to hear your thoughts about it, because I am really not sure if this is some design choice or some issue with my unit.

I've been listening to the 23RM using input signals from 0.5 to 2.5V and apart from the obvious, I don't hear any difference, which is a little disappointing because I had hopes that it might unlock some additional performance.

 

[czervonk]

I've been listening to the 23RM using input signals from 0.5 to 2.5V and apart from the obvious, I don't hear any difference, which is a little disappointing because I had hopes that it might unlock some additional performance.

Looks like your unit doesn’t have issues.

 

[NehPets]

Looks like your unit doesn’t have issues.

Maybe, but is this the level of performance I'd expect at this price point? No. High expectations are the bane of my life.