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That mid runs essentially from 300 Hz to 3 kHz. I am surprised at how unhappy it gets, with broad distortion in the 500 to 800 and 2 - 3 kHz range.

What of rumors of a PA-5 v2?

Very interesting indeed! Do you have any idea what drives THD+N in your case? Could it be very low THD and high N? It it was THD, one would expect a nonlinearity in the transfer function to be the root cause, and that is by defintion going to be level dependent.

You are right, I misread the value due to the typeface used. I still don't see how supply reil induced distortion would be independent of drive level.

The service manual is available, e.g. elektrotanya. I see little wrong with it. Symmetric diff amps (i.e. PNP and NPN pairs), VAS, EF3 with tripple output pairs, regular voltage feedback. What I don't like: - no emitter degeneration on input pairs - no miller compensation - the VAS is loaded to...

Talking about duds, I had another M4 from a recommerce seller on fleabay. They sell stuff that customers have returned for refund and that the big retailers don't want to bother with for testing. Supposedly, it had a few scratches and was missing a few screws on the front plate. It turned out to...

Now I'm confused. Isn't USB-C purely digital? How can a passive adapter make an analog signal available that is not even on the connector? Why would one even think to put a CS43131 if there is no analog output for it?

Yes, but the mic in (channels 1 and 2) stinks in comparison to line in (channels 3 and 4), even at minimum gain. More to follow.

Tangband, the newer revision has no XMOS but rather an Atmel controller. In the picture you linked, which is of an older revision, you can see that the ESS DAC has its own crystal, but the AKM ADC doesn't. The newer revision has an ESS ADC that sports its own crystal. My understanding is that...

Ok, now I get it. The Pro adds the other XMOS chip and I2S, but no analog out.

If you thought that was pretty good, it gets better. I tried all permutations of R and L out (4 resp. 3) on L in (3) and R in (4). Turns out R (4) out into R in (4) is the best. This loopback performance is more than adequate to test most amplifiers while more convenient than having to use...

Here's 1 kHz output at 48 kHz.

Here's 0 dB at 44.1 and 48 kHz sampling rate. 44.1 has all kinds of peaks up to -85 dB - at 48 kHz they don't reach beyond -100. Must be some sort of overflow problem. Why it would be so much worse at 44.1 kHz is anyone's guess.

Ok, here goes. I rechecked the calibration. Setting 0 dB output in ARTA results in harmonics up to -85 dB, so either output or input is clipping slightly. - 1 dB is 4.495 V rms symmetrically at 1 kHz or 4.513 V according to my UNI-T UT139C True RMS meter. Interestingly, it is not truly...

Thanks. So this is the toslink out of the PO 100 Pro --> E70 XLR out --> E1DA? Are there measurements of PO 100 Pro Cinch out --> E1DA? My question pertained to the DAC chip inside the PO 100 Pro.

Is this digital or analog out? The request by Tangband that you quoted seems to imply it is digital out, but for digital out, it looks almost poor. For analog, it looks extremely good. Did you do measurements of analog out of the PO 100 Pro? What DAC does it use?

12 kHz without toggling the LSB?

Sorry, must have saved the same image twice. Will redo and post the 48 kHz spectrum tonight. It does look clean.

This is an M4 recently bought off Amazon Warehousedeals. It has firmware 2.0 and the additional screws on the combi connectors, so I suspect it is v3 but haven't opened it up. Performance in loopback is better than what Amir measured (I suspect on v1), however, I get strange spurious tones...

Well, noise performance compared to Purifi is impressive. Question remains: is there an audible benefit? Regarding distortion, I think I would still prefer the Purifi. The NCx has slightly higher 2nd order distortion, 3rd is comparable, but then it has all those higher harmonics at -130 to...