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Got it. It's much clearer now. I know the Direct Stream DAC was designed so the output of the noise shaper increases at about the same rate as the output filter rolls off, so the noise floor remains approximately the same. Thanks for the clarification. Thanks Bill

A question for MISKA. I have never quite understood the upsampling of 64 DSD to say 256 DSD. The claim I have read is it made filtering easier. That does not make sense for me either. Am I missing something? Thanks Bill

You betcha. I especially detested splitting into two bans and then compressing the HF stuff into the lower band. Why, oh, why not just transmit the file as FLAC? And yes besides being unnecessarily complex it ruined FLAC compression. Although I like it, the marketing BS annoyed the bejesus out of me. In that sense, I am glad it exited stage right. I was pleasantly surprised when I read the bitrate of 64 DSD compared to 96k. Since then I have always thought streaming that was worth a try. Thanks Bill

For me, extra detail retrieval. My friend likes what he calls harmonic resolution rather than out-and-out detail. His DAC sounds 'real', but compared to the Chord, you notice it does not have the same detail. Those old Phillips double crown chips are well known to be euphonic in a way that sounds real to many people, including me. I like the M-Scaler into the Chord directly connected to my speakers. My friend likes the Chord directly connected to speakers but prefers it through a little 2W Set he has into 90 db speakers we both have. He detests the M-Scaler and MQA. I like MQA after the first fold into the M-Scaler. To him, that is the worst of the lot. Strange. Thanks Bill

Back off and understand what is going on with upsampling. Over the years, audio engineers, etc, have noticed even though we can't hear beyond 20 kHz, higher sampling rates sound better. Rob Watts, for example, is a big proponent of this. It is not universally embraced - I know a very experienced Audiophile and honours electrical engineering graduate who likes 44.1k or 88.2k using old Phillips double-crown DAC chips and has designed a DAC around it. It sounds glorious. He is not too fussed about 88.2k over 44.1k but has no issues with it. Going higher, he believes, is useless. He even did a test using a master tape machine, where he recorded the output of a master tape in DSD then used a high-quality conversion program to convert it to 44.1. The difference between the master taper and 44.1 was very slight. I own a Chord TT2 with M-Scaler (as well as one of those double-crown DACS - he will make them on a limited basis if people ask) and have compared the two. Both sound glorious, but in subtly different ways I won't go into. I use the Chord as I prefer directly connecting it to speakers. That said, most tend to agree with Rob and not my friend - higher bitrates sound better, with it improving well into the mHz region. So why not upsample everything to 512 DSD? It is a good approach but has one drawback—the good old brick wall filter. You see, if you use what is called a Dirac impulse (I won't go into the math of what it is - that is somewhat advanced - think of it as an impulse for a very, very short time) on a brick wall 22k filter, you get ringing and all sorts of horrible artefacts. Yuck. This is reduced if you record at higher sampling frequencies. However, there is a problem - we do not have Dirac impulses in the real world. Indeed, looking at what comes out of a microphone in the frequency domain, along with some noise, is a better way to analyse things. The maximum frequency above the noise floor is the vital thing. Provided your sampling frequency is at least twice that Shannon Sampling Theorem guarantees exact reconstruction - no ringing, funny artefacts, etc. - but faithful reconstruction. Many, if not most, recordings don't have any frequencies above 48 kHz, so 96k sampling is perfectly adequate for accurate reconstruction. But they certainly have frequencies above 20 kHz, so you run into the brick wall filter issue. How audible is it? As my friend's experience shows, that depends - we all have different preferences in what sounds best. As a purist, though, I would prefer 88.2k sampling as a minimum. Interestingly, when streaming, DSD 64 is about the same and would be my preference I stream all my. Music from Tidal these days. I like MQA, but that is being phased out. What do I believe it should be replaced with? Lossless MDCT compression, eg https://www.researchgate.net/publication/221578983_Lossless_and_Near-Lossless_Audio_Compression_Using_Integer-Reversible_Modulated_Lapped_Transforms Others may like to comment, but I suspect this would work for either PCM or DSD encoding and could be decoded into either format.

No. But the issue is it audibly the same. The downsampling is pretty neat, but as this thread showed other upsampling filters than what MQA uses can do a good job of producing a good sounding result. I like MQA - to me it sounds a bit leaner - like a layer of grit has been removed. It may be the result of the upsampling filter removing the post ringing - I do not know. I use an M-Scaler to upscale it and it sounds good to me. Shannon's sampling theorem says you get an exact reconstrun of a bandlimited signal with a sinc filter so I don't get this minimum phase filter stuff. Thanks Bill

Knowing how MQA works of course it does. But the claim is time smear is better. I like MQA but will let others argue about the time smear stuff. I do not get it. A sinc filter rings like a bell, with supposedly terrible time smear, but Shannon's sampling theorem guarantees perfect reconstitution of a band limited signal. Can't quite reconcile the two, and neither can others like Rob Watts. And yes I have red Bob Suarts papers on the subject. I am not entirely convinced. For full disclosure I like MQA as far as listening goes. To me the 192k originals sound more harmonically rich but slightly veiled in comparison. MQA is leaner, less rich, but sounds like a layer of 'grit' has been removed. Thanks Bill

I like MQA, but for me that is a big issue. I wish they wouldn't do it. I think they claim cleaning them up or something similar - but I never have heard a difference. Thanks Bill

Well high capacitance cables can send some high bandwidth amps into oscillation and that is VERY audible. But I don't think the cable debate participants have any issue with that one - it's when normal say monster cables are used and people debate if other normal capacitance, inductance, resistor type cables sound better. One amp designer I know thinks that differences in cables are caused by making amps a bit unstable which can increase apparent speed. He designs his amps that way - to be on the verge of instability and are sensitive to some cables. As I have said, and will always say, as a consumer just do a blind test - simple. Thanks Bill

Actually he specifically mentions power cables and he blind tested it. RFI seemed the main culprit he honed in on and one can imagine RFI getting in that way even in speaker cables. I know a couple of cable makers personally and have heard all sorts of strange things I am sure is not expectation bias. One maker says yes RFI is an issue that Rob correctly identifies. But speed is another issue - whatever that is supposed to mean. My first introduction to the difference in sound between cables was 15 years ago when I retired and decided to make Hi Fi my retirement hobby. Anyway I went to my local dealer on the Gold Coast here in Aus (I live st Redland Bay half way between Brisbane and the Gold Coast) to get a new system. Anyway he builds speakers and makes cables as well. I challenged him to demonstrate differences in cables. I won't regale the story of that encounter, but I am now a big cable believer. I find this whole discussion a bit useless really. As a consumer you simply do a blind test - its easy - no need to worry about any discussion about it. Thanks Bill

See: Now Rob is a qualified engineer and claims it at least is partly due to noise floor modulation. The issue is he has not subjected it to the usual scientific standards of publishing it in peer reviewed journals and have the results repeated. That's the problem here - those that know why they sound different have zero incentive to subjects it to scrutiny. For you however its easy. Simply do a blind test - its easy for a single person. If a Hi Fi store refuses to do it for you (its very easy) run a mile - they know what the result will be. Me - personally I trust my ears - but thats just me. Thanks Bill

Cult? - well there is no force involved and nothing happens if you want to leave then rejoin. But belief system? I think Brian Cox's hero Feynman might think something along those lines: And no you cant convince people who have their minds made up. For example here in Aus it is virtually forbidden to even discuss nuclear power - you are howled down from everywhere if you do - even if you are an iconic ex prime minister like Bob Hawke. It's not actually illegal but close to it. It is illegal to build one. Amazing. Thanks Bill

A couple of points 1. Where did you get in the moment from - it took him a couple of weeks and he had been thinking about it for a while. 2 Rob Watts is part of that rest of the engineering world and if you watch the video he explains how you can clearly hear things that are barely measurable or even immeasurable - it shocks other engineers he demonstrates it to as explained in the video so your doubt is understandable. Please take the time to watch it instead of dismissing what I said as hooey. I know only too well the path posts discussing cables goes down which is why I posted it. If you wish to dismiss it fine - I don't care - but others may find it of value.. Thanks Bill

Not sure what FFT has to do with it either and why you mentioned it. FFT is an algorithm for doing a Fourier transform. The FT of a Dirac pulse is all frequencies. We get spikes (usually modeled by Dirac pulses) and hash travelling down all our cables and that sometimes has things of very high frequency. As the video I linked in my post says that causes noise floor modulation which is audible - in fact so audible you can hear amounts that are immeasurable. And no I have not moved cables around - it was just to show that there are reasons for things some tend to dismiss. Please play the video to get my context. No need if you already understand there are things in audio some would say are snake oil but are quite real. It's purpose was to hear from an actual engineer that designs this stuff about what some think are imaginary phenomena. Thanks Bill

Well whats the difference - EFI is any electrical interference - RFI is Radio Frequency Interference. Where to radio frequencies start and electrical interference ends. Seen the Fourier transform of a Dirac Impulse? Thank's Bill