Hi All, I finally picked up my QXR-upgraded 8xpd on the weekend! It's been over 4 months since I ordered it and there have been complications which means my amplifier was updated to the latest specifications. I would not think others ordering now would have similar delays but make sure they are aware of you serial number in case you have an early model like mine. I'll try and post my impressions over the coming weeks as I get time to enjoy it. Having a little one running around I have very little time for decent listening sessions. So it might take some time for my to voice a discerning opinion. But for the eager I have included photos essentially showing the same amplifier just with a QXR badge on it. As you can see the back is identical. My test setup is the following: Roon: iMac 27" i9 NAS: QNAP TS-259Pro+ (4TB mirrored) Switch: Cisco SG 300-28 Small Business Managed Switch CAT6 CD Marantz CD 17 MkIII (SPDIF) Streamers Allo USBridge Curious 0.8m USB Cable iFi iPower Low Noise Power Supply - 5V Other Streamer Allo DigiOne (SPDIF) AMPs 8xpd QXR PSXR Power supply 2 x x200 power mono blocks Power ISOTek EVO3 6 way power board ISOTek (green) cables on 8xpd + PSXR + power board Speakers PMC OB1i Very very very early early impressions: You have to remember I have been without the amp for about 7 weeks so I'm relying on my older impressions. I started by using the DigiOne on the SPDIF input as I had this setup already. The reason is the old DAC only supported 44.1/24bit on the USB. Initially I did not discern much of a difference. Afterward I realised I still had the parametric equaliser enabled on Roon that may have masked much of the improvement. I quickly switched to the USBridge. I went through a few personal listening favorites: Natalie Merchant Live 1999 "The Gulf of Araby" Led Zeppelin - How the West was Won "Going to California" Pink Floyd - Us and Them (very warm track) Radiohead - Let Down Radiohead - No Surprises Dire Straits - Love Over Gold David Gray - Cascade (Live) Dire Straits - Romeo and Juliet U2 - Stay Diana Krall - Live in Paris Overall I'd say "brighter", but not in a bad (harsh) way. The OB1i's are known to be a warm speaker and I felt the new DAC really raised the top end of the spectrum most noticeably. This was also the first time I used the Curious USB cable also I guess there might have been something due to this too. I tried Dark Side of the Moon that I have in DSD but it showed up as some really high rate PCM on the display. Later I realised that there is a setting in Roon that by default would covert DSD to PCM (as Roon did not have an entry for this DAC). Once I changed this to DSD over PCM (DoP v1.0) it worked and the front display showed "DSD64". Cool! So for the record, the fact that Roon does not know this amplifier/DAC does not seem to matter. More impressions later......
Hi Daniel, thanks for responding. I understand that the realtime nature of audio precludes any error correction without the introduction of some form of latency due to the buffering required. I assume with the majority of DAC's, if the DAC is aware of an error in the decoding it, will not attempt to correct the error but will probably extrapolate the output from previous samples (or something of that nature). My point is that if we are aware of when the DAC does achieve zero-errors, then that is valuable information. At that point the digital part of the whole audio-reproduction equation can do no better. And we can stop stressing about that better Ethernet cables or that audio-friendly-switch that's only $500 more. I do understand that digital audio can (and I think often is) flawed and not 'bit-perfect'. But it is reasonable to assume that it can be, if implemented correctly. I'm just wondering how rare a bit error is in a typical middle of the road audiophile system? Judging bit-errors (due to jitter, signal degradation, interference from the power supply, whatever) using your ears seems ludicrous when we could know this information.
I haven't read all the replies on this thread, but I think this is a very good explanation: see below The point to remember is that even so a streamer is digital in and digital out, the actual signal is always analog. We only infer it as being digital because we assume it will be interpreted that way and that the interpretation is perfect. Being an engineer with a Telecom background, what I find confusing is why don't DAC's report their errors. There is (apparently) enough redundancy in a PCM signal for a DAC to KNOW it has made an error. If a DAC would flash an LED every-time it made a decoding error in realtime, we could use that to know when to stop spending money on cables! I guess I just answered my own question.
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