[Maxpain]

   
Others have posted on their practical experiences, for example here:
 
http://www.head-fi.org/t/728236/ifi-idsd-micro-dsd512-pcm768-dac-and-headphone-amp-impressions-reviews-and-comments/4845#post_12100613
 
You can use the search function to find more.
 
The difference between "direct" mode and "preamp" mode is precisely what it says.
 
That is, in direct mode the signal on the RCA's comes directly from the DAC's analogue stage, like it would if you had dedicated DAC with line-outs.
 
In preamp mode the signal on the RCA's additionally adds a volume control and a buffer/preamplifier section, like you would have if you combined a traditional line output DAC with an external preamplifier.
 
You can see the signal flow on the block diagram for the iDSD micro (black & silver) here:
 

 
The preamp in the iDSD micro uses a very high quality J-Fet input integrated amplifier circuit (OV2627 made for iFi) designed to drive 600 ohm loads with very low distortion (< 0.00005% THD & N with a 600 ohm Load). 
 
What's added is a very good sounding pot in front of this amplifier. This is designed and made for iFi by factory founded by people that worked for Noble (still considered the best high end potentiomenter by many) when Noble closed down. It was selected for it's superior sound quality over similar items from other sources.
 
Arguably the same linestage is shared with the headphone section, it drives the headphone buffer which is needed to provide extra current for the headphones and if preamp mode is selected, it also drives the RCA iutputs.
 
You can find dedicated "line stage" preamplifiers and "line controllers" costing serious amounts using the same circuitry and often not even as high grade op-amp's. 
 
For example, a German made $13,800 line preamplifier uses exactly the same kind of circuit, but with amplifier IC's that have more than 10 times the distortion compared to the one in the iDSD micro. 
 
We simply didn't skimp. You really do get a high end linestage integrated in the iDSD micro and you save the money and sonic impact of one RCA interconnect cable.
 
In order to maximize performance it is best to set the gain on the active monitors to the lowest possible and use the gain trim (if present) to set elevated normal listening levels to happen when the iDSD micro is in normal mode and the volume control is around 12 o'clock.
 

 
For a more "scientific" approach you can use a 440Hz/-20dB FS tone, set iDSD micro volume control to 3 o'clock and set the SPL at the listening position using a SPL meter to 82dB for one speaker using the trim on the monitor.
 
The result will then approximate studio condition and THX recommendations for playback.

Thank you for your helping asnwer! Only one more question, you refer to set the micro's volume control to 12 and keep it in normal mode. Isn't normal mode made for the amplifier section of the idsd? I had the impression that when I connect the micro with rca outputs the amplifier is not being used. Does the pre amp section of the micro uses the eco-normal-turbo settings too?
 
Cheers

 

[iFi audio]

  Thank you for your helping asnwer! Only one more question, you refer to set the micro's volume control to 12 and keep it in normal mode. Isn't normal mode made for the amplifier section of the idsd? I had the impression that when I connect the micro with rca outputs the amplifier is not being used. Does the pre amp section of the micro uses the eco-normal-turbo settings too?
 
Cheers

 
What we meant is normal listening level, when the volume knob is between 12 and 3 o'clock. 

 

[Maxpain]

   
What we meant is normal listening level, when the volume knob is between 12 and 3 o'clock. 

I see! I am going to try the micro with the jbl's then and post my impressions!
 
Thank you for your help,
 
Cheers! 

 

[iFi audio]

  I see! I am going to try the micro with the jbl's then and post my impressions!
 
Thank you for your help,
 
Cheers! 

 
Sure, anytime.

 

[Condocondor]

.

 

[Feyded1020]

Does anyone here happen to know any way to reset the iDSD, mine arrived and doesn't work it would seem.

I made some videos of what it was doing with descriptions in the video title area.

I've already opened a ticket and am awaiting a response but was curious if anyone knew a workaround/reset.


https://youtu.be/qtsMhx1VZTQ


https://youtu.be/2KQILkgGIdE

https://youtu.be/9r6PLHnrdfc

Edit: Ive sent the device back and will be ordering a new one as I have faith and understand 'lemons' still exist no matter who makes it. Hoping the second one gives me years of use.

 

[iFi audio]

  What do you think is the main design element that contributes to the sound signature difference between the micro iDSD and iDAC2, and would the micro iDSD BL be different once again? (I haven't listened to that yet).

 
It is notoriously difficult to correlate subjective sonic changes to objective differences, be they in measured performance or correlation to circuit/part details.
 
However, if we have to engage in a specific guess, the key aspects are the Class A line out buffer - which operates single ended, in "deep class A" with (for a line out) very high quiescent current - and the Elna Silmic Powersupply capacitors, which give for want of a better term, a soft, silky sound.
 

Originally Posted by sandalaudio /img/forum/go_quote.gif
 
and would the micro iDSD BL be different once again? (I haven't listened to that yet).

 
Yes, the iDSD Micro Black Edition remains focused on the portable use and this requires some compromises. You will not find "deep single ended class A" output stages or Elna Silmic capacitors.
 
In fact, for a headphone system, the basic design topology of an iDSD micro (silver or Black) and an iDAC 2 micro plus iCAN (and iCAN SE) from DAC to headphone jack are identical. The difference is in actual circuit solutions.
 
Each stage of pure desktop iDAC 2 & iCAN SE  system operates in class A, uses significant discrete circuitry in the signal path and very "high end audio" components extensively. 
 
The transportable 'integrated' iDSD micro omits Class A operation to extend battery life and stuffing so much into a fairly small package limits component quality, though especially in the Back Label we have maxed it out as much as its enclosure and concept allows.
 
In the end, the two alternatives share more in common sonically than they don't. But differences exist, even if the objective measured performance between all options and combinations remains so close, one would be hard-pressed to accept that the measurable differences are enough to cause audibility.
 
Clearly we still have not figured out to measure the parameters that are responsible for "sound quality". 

 

[howdy]

Has anyone compared the Hugo2 vs. BL iDSD in a blind test volume matched?

 

[DomieMic65]

   
It is notoriously difficult to correlate subjective sonic changes to objective differences, be they in measured performance or correlation to circuit/part details.
 
However, if we have to engage in a specific guess, the key aspects are the Class A line out buffer - which operates single ended, in "deep class A" with (for a line out) very high quiescent current - and the Elna Silmic Powersupply capacitors, which give for want of a better term, a soft, silky sound.
 
 
Yes, the iDSD Micro Black Edition remains focused on the portable use and this requires some compromises. You will not find "deep single ended class A" output stages or Elna Silmic capacitors.
 
In fact, for a headphone system, the basic design topology of an iDSD micro (silver or Black) and an iDAC 2 micro plus iCAN (and iCAN SE) from DAC to headphone jack are identical. The difference is in actual circuit solutions.
 
Each stage of pure desktop iDAC 2 & iCAN SE  system operates in class A, uses significant discrete circuitry in the signal path and very "high end audio" components extensively. 
 
The transportable 'integrated' iDSD micro omits Class A operation to extend battery life and stuffing so much into a fairly small package limits component quality, though especially in the Back Label we have maxed it out as much as its enclosure and concept allows.
 
In the end, the two alternatives share more in common sonically than they don't. But differences exist, even if the objective measured performance between all options and combinations remains so close, one would be hard-pressed to accept that the measurable differences are enough to cause audibility.
 
Clearly we still have not figured out to measure the parameters that are responsible for "sound quality". 

are there any plans for Black iDAC2?
from what i understand from your writing is that you suggest the iDAC2 for desktop non portable use more than the black?
Thnx!

 

[sandalaudio]

 

Spoiler: Warning: Spoiler!

 
It is notoriously difficult to correlate subjective sonic changes to objective differences, be they in measured performance or correlation to circuit/part details.
 
However, if we have to engage in a specific guess, the key aspects are the Class A line out buffer - which operates single ended, in "deep class A" with (for a line out) very high quiescent current - and the Elna Silmic Powersupply capacitors, which give for want of a better term, a soft, silky sound.
 
 
Yes, the iDSD Micro Black Edition remains focused on the portable use and this requires some compromises. You will not find "deep single ended class A" output stages or Elna Silmic capacitors.
 
In fact, for a headphone system, the basic design topology of an iDSD micro (silver or Black) and an iDAC 2 micro plus iCAN (and iCAN SE) from DAC to headphone jack are identical. The difference is in actual circuit solutions.
 
Each stage of pure desktop iDAC 2 & iCAN SE  system operates in class A, uses significant discrete circuitry in the signal path and very "high end audio" components extensively. 
 
The transportable 'integrated' iDSD micro omits Class A operation to extend battery life and stuffing so much into a fairly small package limits component quality, though especially in the Back Label we have maxed it out as much as its enclosure and concept allows.
 
In the end, the two alternatives share more in common sonically than they don't. But differences exist, even if the objective measured performance between all options and combinations remains so close, one would be hard-pressed to accept that the measurable differences are enough to cause audibility.

 
Clearly we still have not figured out to measure the parameters that are responsible for "sound quality". 

 
Thanks for the very detailed and clear explanation.
 
I do notice a significant sonic difference, and I am hard pressed to find any line level USB DAC that can surpass the micro iDAC2.
 
I know iFi's good sound quality doesn't come purely by coincidence or by random accident, so I was curious about where the effort was placed to go beyond the textbook circuits.

 

[Joseph Lin]

Does anyone here happen to know any way to reset the iDSD, mine arrived and doesn't work it would seem.

I made some videos of what it was doing with descriptions in the video title area.

I've already opened a ticket and am awaiting a response but was curious if anyone knew a workaround/reset.


https://youtu.be/qtsMhx1VZTQ


https://youtu.be/2KQILkgGIdE

https://youtu.be/9r6PLHnrdfc

Edit: Ive sent the device back and will be ordering a new one as I have faith and understand 'lemons' still exist no matter who makes it. Hoping the second one gives me years of use.

My first BL iDSD has exactly the same symptom when it first ran down the power and the music was cut off. I tried to charge it overnight but it displayed alternating Blue-Red led even the second day. I measured how much current was going into the device and it was 0mah. Since it was new so I returned it. Now I am very scare of letting it run down the battery. If you are still in the return period, my suggestion is to return it.

 

[Vartan]

Does the RCA line out when set to direct on the iDSD BL operates in pure class A?

 

[iFi audio]

  Does the RCA line out when set to direct on the iDSD BL operates in pure class A?

 
This depends upon the load. The line out is driven by an integrated amplifier circuit with 2.2mA quiescent current. Some of this will be the "class A" current for the output stage. It is hard to be sure just how much, but lets presume it is 1mA as an educated guess based on the general performance. 
 
As the output stage is push-pull, +/-2mA peak current is available with 1mA quiescent current.
 
So as long as the complex load impedance remains above around 2 kOhm across the audio range, the output remains in push-pull class A. 
 
However, the audio performance of the integrated amplifier circuit will be degraded before class A is left, it is better to keep the load impedance at >= 10 kOhm and to use low capacitance cabling.
 
This again holds true for pretty much any DAC/preamp using integrated amplifier circuits without added buffers.
 
By comparison, the special discrete buffer in the iDAC2 micro operates at around 7mA single-ended and places by the nature of it's circuit design the output stage of the integrated amplifier circuit also into single ended class A.
 
So in comparison, the circuit operates fully single ended and remains in class A for loads as low as 400 ohms and shows no performance degradation with loads as 600 ohms, as the actual load of the integrated amplifier circuity in this case will be around 120 kOhm, ensuring best linearity.

 

[chawya22]

I'm having a problem where the first second or so of music is muted when I manually switch tracks. My source is a MacBook Pro (10.12.3) running Audirvana Plus 2.6.5, Tidal Desktop 2.1.2.177 and the iFi FW is 5.2. If I play tracks consecutively, all is well, just when I replay or skip to the next track. I did try a search but I guess I didn't choose the right wording if this problem has been discussed before.

 

[DomieMic65]

  I'm having a problem where the first second or so of music is muted when I manually switch tracks. My source is a MacBook Pro (10.12.3) running Audirvana Plus 2.6.5, Tidal Desktop 2.1.2.177 and the iFi FW is 5.2. If I play tracks consecutively, all is well, just when I replay or skip to the next track. I did try a search but I guess I didn't choose the right wording.

I guess this has to do with the latest firmware
It started happening after 5.2 was launched.. may be a biger buffer? I don't know if I am using the correct term beacause I have no technical knowledge
in my case it happens some(many) times but if i go back and play again the track it's OK