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GUTB

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  1. How was it determined that there was no time correction?
  2. It's true that MQA is lossy, but it seems that they've successfully identified what can be lost and still maintain high resolution audio. With MQA-CD specifically there does appear to be a loss of definition vs higher bitrate masters (176-384), so if it's a choice between MQA-CD and DXD or high-rate DSD than MQA-CD would be the last choice. However, high-rate DSD and DXD (or 176-192) don't have physical media (I wonder why?). So if you want physical digital media, and a lot of audiophiles (especially in Japan) do, there's 2 choices currently: SACD and MQA-CD. SACD isn't lossy, but it's stuck with a lot of noise close to the audio band which requires an aggressive filter. It's not optimal for DSD, which really takes off at DSD-256. With MQA-CD, it seems to result in lossless-like performance up to 96 kHz. I also consider SACD to be somewhere around the 96 kHz level....but DSD isn't directly comparable that way so in some cases it provide great results that can't be matched by any PCM, certainly not on a CD format. Another thing. I'm not really sold on the benifit of the time-domain correction. There is absolutely something happening to the sound which some of you guys say you don't like. Personally I don't mind it, but it doesn't make things sound more analog if I were to compare to my vinyl. So, if it's an analog master than SACD is still probably the best physical format. However. These huge libraries owned by the labels can be batch-converted to MQA, they can be just as easily pumped out in MQA-CD. It's turning out that for many titles on physical media MQA-CD is going to be the only high-res format available.
  3. It's not gobbledygook but rather a functional compression scheme. From my own testing MQA-CDs played back in a non-MQA system are indistinguishable from regular CDs (using the MQA test CDs) in casual listening. I haven't performed a detailed listening comparison so there may be mild artifacts. I'm actually not sure if it's just the least significant bit dedicated to MQA data. Using a MQA-CD capable system (in my case, a Mytek Liberty and a regular CD transport connected via SPDIF) the quality improvement is on the level of a 96 kHz master, and significantly inferior to high-rate DSD and DXD masters. Bear in mind that all (most?) of these MQA-CDs are coming out of Japan and being mastered onto UHQCD media. In testing UHQCD (again using a sampler pack to compare UHQCD vs regular CD with the same tracks) I found there was a mild but noticeable improvement to lower frequency definition, something you normally don't get with MQA so it's not as simple as saying MQA-CD is just like a 96 kHz PCM or a low-rate DSD (SACD). It's been a long time since I listened to SACD so I can't honestly say that MQA-CD is the best physical digital format currently.
  4. So, ESS released a new chip a little while ago, the 9068AS. This part is unique as it is the first DS-style DAC chip which has MQA unfolding built into the silicon. The Gustard DAC-X16 was the first product on the market to use this chip for $500 -- so I just had to pick one up. After a day of burn-in I sat down to test it out...and found that is wasn't detecting MQA-CD from the coax input. Reading the spec sheet for the chip it says that it unfolds "decoded MQA streams"...meaning that it doesn't decode them. It needs a first decode stage first, and as usual with these Chinese DACs that's on the copy-pasted XMOS controller. Very disappointing, I was hoping this would be a good alternative for getting MQA on all the inputs except for a few products that do it right like Mytek DACs. Anyway, maybe the on-silicon unfolding performs substantially better than doing it externally off-die? I'll have to test this, stay tuned for my findings.
  5. Just opened it up look and I can't see them, they're fully covered by another component directly in front of them so I can't read the text on the front. I don't even know if they're regulators I just assume they are because they're attached to heatsinks. Also I've decided NOT to return the VTV. The reason is that on Audiogon someone commented that the Weiss opamps destroyed all the others and was a game-changer for him. So okay, I went and ordered some Weiss...these are very large and very expensive parts. $170 for each one, and they are single opamps meaning I need a total of four, so that's $680 for the lot...going into a $1k amp. So between these and the input boards the actual price is now around $2k. They're on their way and I should get them next week.
  6. Just a note. I listened to the Schiit live Q&A session today and heard that the new Schiit CD transport is going to have a USB output capable of connecting to USB DACs. That's big, it's the only transport capable AFAIK that can do this, and there's no digital interface that I know of that offers SPDIF-to-USB functionality. That means MQA-CD is opened up to a much larger pool of MQA DACs.
  7. Oh good, they can count my potential business I may have done with them in the future gone forever. Trust is a precious commodity in this industry and if they don't care to lose it than I know where not to place it.
  8. Okay so I plugged my reference mains into the input of the 500VA balanced isolation transformer and the VTV into one of the outlets using an Audio Envy power cable. This is the transformer I have: https://aliexpi.com/ugvH Also, by happenstance, I got in a new preamp, a Mbl 6010 clone: https://aliexpi.com/pxKz The new preamp has balanced input and output and low noise / distortion specs. I thought I'd throw this into the chain as well. The Freya is high-bandwidth and has a JFET buffer stage option, but I never trusted I was getting good results from this unit. It's been burning in for a day now. So, there MAY be something to this power quality argument. I listened to some tracks, some Bluegrass that makes me especially happy to see if engagement has improved. And....I think there may be an improvement. I felt I was able to get into it at least somewhat, something that the amp has failed to do up until now. Maybe the preamp has something to do with it. So I'll hold off on returning it just yet. Dynamics are even worse but that has to be the preamp burning in (I hope and I don't need a larger transformer and those get pricey to ship from China).
  9. I was using my reference mains which is a Lessloss level 1 filtering cable + Lessloss Firewall 64X plugged into a Furutech outlet. My listening room has only audio gear plugged in and no lights / fans turns on. I suppose I COULD try it through my 500VA balanced isolation transformer before I pack it up...but I had tested it against a stock black cable plugged into another common outlet in the room and I don't think there was any difference. On my reference there were large upgrades to sound with this setup.
  10. In reality, the sound from the Purifi is less resolving and more muddled than from the Odysseys, with or without tubed preamps and with digital or vinyl. It's not awful (after upgrading the input boards) but if you think this is high-end sound you honestly don't know what high-end sound is. Odyssey amps are good, but I've heard better. I also wouldn't describe the sound of the Purifi as being dry, cold or lifeless unlike most other class Ds have struck me as. I believe Purifi had solved that particular problem. But the death-blow to class D remains, the utter boredom and lack of engagement. I can't narrow it down to a particular technical aspect as technically speaking it's okay across the board. The only thing I can come up with is that something about class D is ugly to the ear-brain system which causes listener fatigue. I gave this more than a fair shake. It was found wanting in the end. From a technical perspective the sound was what most would consider "good". It's true that I have higher expectations than many on the forum, but even I can't point to any technical aspect of the sound and call it "bad". Dynamics, microdetail / resolution was a step down from my reference, but just a step. The horrible midrange was solved by the input board and opamps. I guess it images unusually high, but I don't think that's a deal-breaker and besides that it imaged just as well as my reference. Perhaps even the dynamics could be helped by an upgraded power supply. Maybe higher-end opamps could even bring the resolution up to reference. But the killer fatigue IS a deal-breaker, and opamps won't fix that. Tubes didn't fix it as my all-tube preamp using all NOS tubes didn't change that. You can blame it on my personal preference but I think perhaps you should open your mind the possibility that class D still garbage due to intrinsic flaws in the technology which haven't been solved yet. I may still try the the other GaNFETs, those might legitimately be game changers. The Cherry amps might be the lone exception as well as they use some kind of parallel switching tech that allows them to get much higher bandwidth than traditional possible. I have a little Cherry stereo amp but it's too weak for my speakers so I can't really use that as a reference to make a judgment call on it, but I will say that it also has a full tonal quality similar to the Purifi and unlike other class Ds.
  11. So, the Purifi is going back. After giving the new input boards and Sparkos opamps several days of burn-in after which it doesn't appear to improve any further I gave it a listen. I tried it with both the Yaqin B-2T all-tube SE preamp and my Freya using all-balanced connections. Digital is from my reference digital source (custom audio PC) to a Yggdrasil Analog 2. Also tried by vinyl system with it. Ugly midrange problem: appears to have been solved by the new input boards and opamps. Midrange quality significantly improved and is now almost as good as the reference (Odyssey Kismet / Stratos). Still a little less resolving / muddled compared to the reference. Dynamics seems to have improved, but not by a huge amount. It might also be in my head but my perception is that dynamics have improved somewhat. No other changes particular stood out to me. The VTV Purifi with the upgrades appears to be just one step below my Odessey Kismet and Stratos ($1500 used, later $800 used). With upgrades the Purifi is $1400. Essentially this is a budget-performance amp at a budget price. Mind you the Odysseys which are not high-end are still a great value in American hi-fi and if you get them used you can get a decent amp at a budget price. I would say the VTV is reasonably priced for the amount of performance it provides which amounts to "okay". This technical performance. There is one other issue that is absolutely killer: The total lack of engagement. I tried listening to it, but from start to end, I felt like I was forcing myself. I was never involved or engaged in the music. At first I was willing to consider that it was the ugly midrange problem which was doing it. But after that was solved there appeared to be no other excuse. Dynamics, microdetails, etc, is just one step down from the reference. They're fairly close. I fixed the cables and tested various configurations, nothing helped. I just didn't enjoy the sound, and that reason had no particular reason related to sound technicalities. In the end -- it's the usual, traditional death blow to class D, fatigue. There's something it does which is murder on the ear-brain system. I used to associate that with the lack of bandwidth and destructive output filter. I was told that self-oscillating amps don't have this issue by doing the filtering by using feedback; I have no idea how that works but if it's true then there's something else doing it. But it's still there. Basically it's still unlistenable. Those of you who think you like your class D, I recommend being honest with yourself. Do you REALLY enjoy listening to you music? When was the last time you turned on your class D and got sucked in? Has it ever happened? Is your system spending more and more time left alone and you tell yourself it needs this or that upgrade? Once again I'm forced to accept that class D has serious killer problems and I doubt it's a phenomena I'm alone in experiencing. I don't think it's matter of discernment or having experience with high-end audio.
  12. Right from the beginning you should hear a greater dynamic presence or "pop" from the piano on the DXD. Drumstick taps sound more "present", there's an overall sense of dullness in the MQA-CD vs DXD. Pay attention to the bass starting at 1:55 in the DXD you should hear deeper into it making it seem more present / real.
  13. That’s interesting. To me the difference between MQA and DXD was minor, but the difference between DXD and MQA-CD was pretty significant. My system for this test was my custom audio PC, Mytek Liberty + linear power supply, Mjolnir 2, TH900 with balanced cables. What were you listening with?
  14. The upgrade input boards and Sparkos opamps came in today. I installed them and the amp is now burning them in. I’ll refrain from posting early observations because those are always defunct within the first day of burning in so I’ll hold off this time. I’ll check in on it regularly to see where it’s at but I plan on giving it at least 100 hours.
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