dir
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I did not have experience with Schiit converters, but I'm not suprised by bad linearity on low level singals. Its typical for R-2R conversion.
Also I'd like to share my personal observations about Micro DSD.
Generally speaking, converter has three modes of a digital filter. I understand that you measured the Standard. The Minimum Phase gives the expected frequency drop. The strangest one is Bit-Perfect, which for some reason is recommended for listening by the iFi in manual. The frequency response here has too early drop, the aliasing noise is not suppressed at all, and the noise level rises above the level of -100 dB, which makes it meaningless to reproduce 24-bit content, in fact with such a level of noise Bit-Perfect provides 16-bit resolution only.
That graph shows an example of what a low-level sine (-90 dB) turns into Bit-Perfect mode
Since the chip DSD1793 provides only two filters Sharp and Slow - i.e. Standart and Minimun Phase in our case, then, probably Bit-Perfect is a DAC operation in NOS mode with filters disabled.
The manufacturer emphasizes that at a frequency of 384 kHz DAC works in Bit-Perfect mode, but actually it does not make sense on the specified chip. The sampling limit for the DSD1793 is 200 kHz, so any DXD will be filtered at a frequency of 100 kHz, which is confirmed by the measurements. The format limit for such a device is PCM 192 kHz and DSD64, all that is higher is just the characteristics of the receiver, not the true DAC mode.
Also i was noted on the graphs of iFi micro iDSD is catching 50 Hz from power supply of Sony laptop via USB. Of course, measurements shows as a very small tip, below the hearing threshold value, but for clear result my laptop should be switched to an autonomous power supply mode.
Also I'd like to share my personal observations about Micro DSD.
Generally speaking, converter has three modes of a digital filter. I understand that you measured the Standard. The Minimum Phase gives the expected frequency drop. The strangest one is Bit-Perfect, which for some reason is recommended for listening by the iFi in manual. The frequency response here has too early drop, the aliasing noise is not suppressed at all, and the noise level rises above the level of -100 dB, which makes it meaningless to reproduce 24-bit content, in fact with such a level of noise Bit-Perfect provides 16-bit resolution only.
That graph shows an example of what a low-level sine (-90 dB) turns into Bit-Perfect mode
Since the chip DSD1793 provides only two filters Sharp and Slow - i.e. Standart and Minimun Phase in our case, then, probably Bit-Perfect is a DAC operation in NOS mode with filters disabled.
The manufacturer emphasizes that at a frequency of 384 kHz DAC works in Bit-Perfect mode, but actually it does not make sense on the specified chip. The sampling limit for the DSD1793 is 200 kHz, so any DXD will be filtered at a frequency of 100 kHz, which is confirmed by the measurements. The format limit for such a device is PCM 192 kHz and DSD64, all that is higher is just the characteristics of the receiver, not the true DAC mode.
Also i was noted on the graphs of iFi micro iDSD is catching 50 Hz from power supply of Sony laptop via USB. Of course, measurements shows as a very small tip, below the hearing threshold value, but for clear result my laptop should be switched to an autonomous power supply mode.