In other news: I received my DX3Pro today, purchased from ebay seller topssale (was mentioned earlier in this thread). With ebay coupon, total cost was around $160.
Anyway: first annoyance, my remote didn't come with a battery. Am I overlooking it in the box? Or did everyone else's also not come with a remote battery? It calls for CR2032. I have CR2016 on hand, which are the same diameter and voltage (3v), just half the thickness. Fortunately the remote battery holder accepts the thinner battery.
Otherwise, initial impressions are good, but I literally just unboxed it and fired it up. At the moment, I'm using it as a standalone DAC, USB connected to a Raspberry Pi running MPD (OS is DietPi). So far I have only heard the relay clicking when switching between songs with different sample rates and/or bit-depths. Seeking within tracks and changing to tracks of the same sample rate and bit depth does not result in any clicking.
Earlier in the thread, I asked about USB pass-through of volume control. I
think this does work, but I'm not 100% sure. But it does present a hardware mixer device to ALSA. I believe XMOS receivers without such capability don't provide a mixer device.
Code:
root@dietpi-music:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: sndrpihifiberry [snd_rpi_hifiberry_dac], device 0: HifiBerry DAC HiFi pcm5102a-hifi-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Pro [DX3 Pro], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
root@dietpi-music:~# amixer -c 0
<no output>
root@dietpi-music:~# amixer -c 1
Simple mixer control 'DX3 Pro ',0
Capabilities: pvolume pvolume-joined pswitch pswitch-joined
Playback channels: Mono
Limits: Playback 0 - 127
Mono: Playback 76 [60%] [-51.00dB] [on]
Simple mixer control 'Topping Internal Clock Validity',0
Capabilities: pswitch pswitch-joined
Playback channels: Mono
Mono: Playback [on]
Note that card 0 is a RPI-HAT (my own design, simple tda1387-based DAC). And you can see card 0 has no mixer, whereas the DX3 Pro (card 1) does.