Hi,
First review here, so don't hesitate to tell me if you see something odd.
I just bought an Antelope Amari for mastering work and Antelope's specs were not precise enough to my taste.
Since the APX555 was just there I did some measurements. I tried to be consistent with most measurements I've seen on the forum.
View attachment 344775
DAC:
Inputs: ASIO
Outputs: XLR
Fs: 44.1kHz
Monitor:
Here's the monitor with a 0dBFS input.
View attachment 344777
Frequency Response:
Here's a sweep at 0dBFS. Keep in mind the left axis scale has 2dB amplitude.
View attachment 344780
THD+N:
THD+N for a 0dB sweep (sorry for the timeout).
View attachment 344781
Linearity:
View attachment 344782
SNR & Dynamic Range:
0dBFS at 1kHz. SNR (left) at 133dB and AES 17 Dynamic Range at 132dB.
View attachment 344783 View attachment 344784
IMD Ratio:
This measure kept timing out this is the best I could get.
View attachment 344785
Sinad vs Measured Level:
View attachment 344786
ADC:
Inputs: XLR
Outputs: ASIO
Fs: 192kHz
Monitor:
Monitor for a 23.9dBu input.
View attachment 344789
SNR & Dynamic Range:
Signal to Noise Ratio (left) from 0dBFS is 128dB. AES17 Dynamic Range is 124dB. Measured with a 20kHz bandwidth.
View attachment 344790 View attachment 344791
Frequency Response:
Taken at +23dBu.
View attachment 344792
IMD Ratio:
View attachment 344793
Headphone Amp:
Input: ASIO
Output: HP1 (Unbalanced then balanced)
Fs: 44.1kHz
Had to so measurements are in mono. So no channel matching etc sorry.
The headphone amp has a "membrane weight compensation" setting. The lower it is the louder is it's output.
All measurements were made with that setting in its minimum position of -4.6 Ohm.
Unbalanced SNR:
600 Ohm Load, from 0dBFS
View attachment 344794
Unbalanced THD+N Ratio vs Measured Power:
Firstly 300 Ohm resistive load
View attachment 344796
Then 32 Ohm resistive load
View attachment 344797
Balanced SNR:
600 Ohm resistive load, from 0dBFS
View attachment 344798
Balanced THD+N vs Measured Power:
Firstly 300 Ohm resistive load
View attachment 344799
Then 32 Ohm resistive load
View attachment 344800
Official Specs:
View attachment 344802
Closing Thoughts:
I'm curious of what you think about these.
The DAC A-Weighted SNR is 135.7dB so around 2dB off from the 138dB announced. I do like the distorsion measurement though.
I'm not sure what to think about the headphone amp. The unbalanced output seem to be better.
The ADC looks pretty good except that weird plateau in IMD starting at +5 dBu.
One selling point still remaining is the oven controlled clock as I couldn't set up the j-test.