- Oct 20, 2021
Great, thanks!Yeah, I was just about to post my updated results.
I did some RMAA measurements again, because the last time I used some janky improvised cables that were actually affecting the results in some cases. Or a loose connection here and there can mess up the results...
Posting the screenshots of the summaries, but you can find the full reports and a few more tests in the attached zip:
RCA 3-4 outputs on the UMC204HD to inserts, max volume:
View attachment 160692
(RCA 3-4 outputs have the best performance. RCA 1-2 and the main outs measure almost the same, but with slightly worse crosstalk.)
Apple USB-C on the phone to inserts, max volume:
View attachment 160693
Headphone out on the UMC204HD with the Philips SHP9500 headphones (using a splitter) to inserts, volume at 12 o clock:
View attachment 160694
Apple USB-C on the phone with the Philips SHP9500 to inserts, max volume:
View attachment 160695
I didn't include the front inputs measurements, because they're the same as last time and they are still bad.
But the insert line in performance is actually good and this time it beat the onboard Realtek.
The Philips SHP9500 are 32ohm headphones.
The maximum volume for the headphone test on the UMC (the one in the zip that doesn't say volume) was at a bit over half. That's also about the max before RMAA started to complain about too much distortion in the signal.
The max I'd use in practice with these headphones is around 11 o'clock volume (without the splitter).
Audio that's played on the UMC204HD from Windows leaks into its inputs, mostly into the right channel. This happens even without any headphones or speakers being plugged in. I'm not sure how much this affects the loopback tests, I didn't investigate too much, it's just something I noticed at some point. You can see it with some recording app that shows input levels when you play loud sounds with the UMC as the playback device.
FR plots for the cases with phones result in conclusion the phone amp has got rather big output impedance.