MEASUREMENTS
Before measuring the Cambridge MXN10 with my Audio Precision SYS2722,1 I installed the StreamMagic app on my iPad mini. After the Cambridge’s Ethernet port had been connected to my network, I used the app to perform a factory reset and check that the firmware was up to date. I measured the Cambridge using test-tone files stored on a USB stick plugged into the processor’s rear panel or via my network with Roon. (The Cambridge is a Roon Ready device.) TF told me that he auditioned the Cambridge with its output level set to Fixed, so all the testing was performed in that mode. I then used the app to enable Preamplifier mode and repeated some of the tests at various volume control settings. (The StreamMagic app’s volume setting was echoed by the Roon app.)
In both Fixed mode and in Preamplifier mode with the volume control set to the maximum of “100,” the MXN10’s maximum output level at 1kHz was 2.1V into 100k ohms. The app’s volume control operated in 0.75dB steps—a setting of “80” reduced the analog output level by 15dB. (The volume control doesn’t affect the output level at the S/PDIF digital outputs.) The MXN10’s single-ended output preserved absolute polarity (ie, was noninverting), and the output impedance was a moderately low 437 ohms from 20Hz to 20kHz.
Fig.1 shows the MXN10’s impulse response with 44.1kHz data. The reconstruction filter appears to be a long minimumphase filter, with all the ringing following the single full-scale sample. This filter’s ultrasonic rolloff (fig.2, magenta and red traces) reaches full stop-band attenuation at 24kHz with the aliased image at 25kHz of a full-scale tone at 19.1kHz (cyan, blue) suppressed by 87dB. The harmonics associated with the 19.1kHz tone all lie below –96dB (0.0015%). Fig.3 shows the MXN10’s frequency response with data sampled at 44.1, 96, and 192kHz. The response with