iFi Micro iDAC2: Mode LED color is always white in PCM

Connection with external Audio Devices USB DAC
1

Hello!
Playing with Audirvana DSD files, the LED lights correctly:
Blue for DSD64
Magenta for DSD128 and DSD256

But playing PCM files, the LED is always white, indicating 384kHz (the maximum rate the DAC is capable for)

I use:
DAC: iFi Micro iDAC2
MacBook Pro 16 with Big Sur (but the same with an older Mac with Catalina)

I have tried different files, from CD 44.1kHz/16bit to 192kHz/24bit.
The debug info shows correctly:
Active Sample Rate: 44.1kHz
Active Sample Rate: 88.2kHz
Active Sample Rate: 96kHz
Active Sample Rate: 192kHz

but the LED is always white and NOT
Green for 44/48kHz
Yellow for 88/96kHz
Cyan for 176/192kHz

Upsampling is DEACTIVATED.
If I force the upsamping to DSD64 or 128, the LED color became blue or magenta correctly.

For every other PCM audio file, is always white.
Does this mean that every PCM file is always upsampled to the maximum working frequency of the DAC?

What’s wrong?

Also, plying a CD flac file 16/44.1, Audirvana shows in the bottom right corner of the windows indicates 32/44.1
Does this mean that the 16 bits are sent at the maximum resolution the DAC is capable of?
(The same for the 24bit audio files.)

I think this won’t affect the audio quality, as the “number” contained in a two bytes sequence can be stored correctly in a 4 byte sequence (the 16 or 24 bit sequence will stay perfectly in a 32 bit space).

The main question however is: I would like to know how to let the DAC decode the PCM files at their native rate without upsampling.

Thank you so much for your support!
Mauro

Debug info:

Audirvana Mac Version 3.5.42 (3572)
macOS 10.16.0 with 32768MB RAM

Registered to Mauro Bricca

SIGNAL PROCESSING:

Polarity Inversion:
	Globally: OFF
	Per track: OFF
Effects plugins NOT ACTIVE

UPSAMPLING:
SoX not in use
SoX filter parameters
Bandwidth at 0dB = 99.5
Filter max length = 30000
Anti-aliasing = 100
Phase = 66

AUDIO VOLUME:
Max allowed volume: 100
Replay Gain: None
SW volume control: OFF

LIBRARY SETTINGS:
Sync list: 1 folders
AUTO: /Volumes/Archivio/Musica
iTunes/Music library synchronization: last synchronized on Mon Nov 16 22:28:25 2020

Library database path: /Volumes/Archivio/Musica/AudirvanaPlusDatabaseV2.sqlite

ACTIVE STREAMING SERVICES
Qobuz: Connected as Qobuz Studio

=================== AUDIO DEVICE ========================

CoreAudio audio path, buffer I/O frame size: 512

Max. memory for audio buffers: 1102MB

Local Audio Engine:
Exclusive access: Enabled
Integer mode: Enabled

Preferred device:
iFi (by AMR) HD USB Audio Output
Model UID:iFi (by AMR) HD USB Audio:20B1:3008
UID:AppleUSBAudioEngine:iFi (by AMR):iFi (by AMR) HD USB Audio:00000000:1

Active Sample Rate: 44.1kHz
Hog Mode is off

Bridge settings:
Sample rate limitation: none
Sample rate switching latency: none
Limit bitdepth to 24bit: OFF
Mute during sample rate change: ON

Selected device:
Local audio device
ID 0x2c iFi (by AMR) HD USB Audio Output Manufacturer:iFi (by AMR)
Model UID:iFi (by AMR) HD USB Audio:20B1:3008 UID:AppleUSBAudioEngine:iFi (by AMR):iFi (by AMR) HD USB Audio:00000000:1

8 available sample rates up to 384000Hz
44100
48000
88200
96000
176400
192000
352800
384000
Audio buffer frame size : 14 to 4096 frames
Current I/O buffer frame size : 512
Volume Control
Physical: No
Virtual: No
MQA capability
Auto-detect MQA devices: Yes
MQA Renderer device
DSD capability: DSD via PCM 1.0
Device audio channels
Preferred stereo channels L:1 R:2
Channel bitmap: Ox3, layout:
Channel 0 mapped to 0
Channel 1 mapped to 1

Audio channels in use
Number of channels: 2
Use as stereo device only: No
Simple stereo device: Yes

1 output streams:
Number of active channels: 2, in 1 stream(s)
Channel #0 :Stream 0 channel 0
Channel #1 :Stream 0 channel 1

Stream ID 0x2d 2 channels starting at 1
16 virtual formats:
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 384kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 352.8kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 192kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 176.4kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 96kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 88.2kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 48kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Float 44.1kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 384kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 352.8kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 192kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 176.4kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 96kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 88.2kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 48kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 44.1kHz

16 physical formats
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 384kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 352.8kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 192kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 176.4kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 96kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 88.2kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 48kHz
2 ch Mixable linear PCM Interleaved 32 little endian Signed Integer 44.1kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 384kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 352.8kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 192kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 176.4kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 96kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 88.2kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 48kHz
2 ch Non-mixable linear PCM Interleaved 32 little endian Signed Integer 44.1kHz

Local devices found : 2
Device #0: ID 0x2c iFi (by AMR) HD USB Audio Output Manufacturer: iFi (by AMR) Model UID: iFi (by AMR) HD USB Audio:20B1:3008 UID: AppleUSBAudioEngine:iFi (by AMR):iFi (by AMR) HD USB Audio:00000000:1
Device #1: ID 0x4f Altoparlanti MacBook Pro Manufacturer: Apple Inc. Model UID: Speaker UID: BuiltInSpeakerDevice

UPnP devices found : 1
Device #0: ID 0x0 [LG] webOS TV SK8500PLA UID: uuid:67b5b83f-5c88-6c64-4954-67a2b35271be Location: http://192.168.178.66:1372/

2

Hello @MauroBricca,

When you play a file in Audirvana, does Audirvana detect the proper sample rate in the bottom right corner of your screen? Does the track is played normally or it’s accelerated?

3

Hello Damien,
in the bottom right corner it’s always correctly indicated.
The playback is perfect, not accelerated, and always good sounding.

My DAC does not have a display where you can see the numbers indicating the sample rate and frequency.
It has a LED that changes the color, following this scheme:
Blue for DSD64 (2.8/3.1 MHz)
Magenta for DSD128 (5.6/6.2 MHz) and DSD256 (11.2/12.2 MHz)
(and these are correctly indicated on the DAC with the corresponding color, when these kind of files are played with Audirvana)

then:
Green for PCM 44/48kHz
Yellow for PCM 88/96kHz
Cyan for PCM176/192kHz
White for DXD352/384kHz

but with PCM files, the DAC LED is always white…

so I suppose that the signal could be upsampled in some way when sent to the DAC
but in the bottom right corner it’s always correctly indicated, e.g. “24/96kHz Stereo”
Can be the operating system?

DAC: iFi Micro iDAC2
MacBook Pro 16 with Big Sur (but the same with an older Mac with Catalina)

Note: also using iTunes, VLC, YouTube, Spotify, other software… that led is always white (384kHz).

Thank you!

4

Okay, i think you might consider ask iFi about it as the issue you have can be related to your Mac or your DAC, either way the best thing to find this out is to contact them.

5

Thank you Damien, I will try to contact the DAC manufacturer.
Audirvana + this DAC sound amazing, that was just my technical curiosity.
Probably the operating system with this DAC always use the maximum resolution and frequency allowed by the hardware…
Thank you so much for your support,
ciao from Italy,
Mauro

6

Hello @MauroBricca

I also have an iDAC2, and some firmware will cause what you describe. The GTO filter does upsample all PCM and you get the white indicator. I’m using firmware 5.3c, I don’t recall if other versions have the GTO filter, but if they do the same result will happen. DSD playback will give different LED colours.

Hope that helps.

7

Thank you Airdronian!

Yes, I have installed the newest firmware:
5.3c – GTO Filter - Release date: 10 Sept 2018

My fault, I didn’t read the release details on iFi web site…

In fact, they say that:

All PCM LED colours will be the same colour due to GTO filter (white)

Pros:
GTO filter which upsamples USB audio (please read here for more information)
and there is also an interesting explanation about that:

Cons:
SPDIF output disabled (on USB to SPDIF capable units)

So it is confirmed the all the PCM sound is upsampled to the maximum frequency supported by the DAC, as I had supposed…

This seems to be a further enhancement in sound quality.

So Audirvana is “innocent”: the software always send the signal correctly (eg. 96kHz/24bit) and the DAC internally works the signal at 384kHz/24bit.

The reproduced sound is definitely very good, in my opinion, so the “white led” is not an issue.

I confirm also that, with the latest firmware, the the Spdif output is now dead…

Thanks to you all for the support,
Ciao!

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