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Wow. I can’t believe this PSU thing is generating so much controversy. I don’t own a Qutest. Half the time, when Rob Watts writes something on Head-Fi, I don’t really understand what he’s saying. Takes re-reading it several times and thinking about it to understand a little more. Moreover, he changes his mind over time. Or he would say, he was expecting other people to use better source components or pre-amp/amp so the problem is not with Chord products/supplied PSUs but he acknowledges that a problem can exist.

 

Going to Head-Fi and reading Rob Watts thoughts, the following is what I got even though I understood like 30% of what he’s saying:

there is no ground with the supplied Qutest PSU; and that is done on purpose, as it eliminates the possibility of ground loops.
for sure ground loops are the major issue, as it's a low impedance direct connection. The problem with a non ground connected PSU is much smaller again, as it is capacitively coupled to the mains and then to ground via the PSU transformer; so here we have the possibility of another loop; but it's capacitive, so only applies with RF signals, not leakage currents in the audio bandwidth. Clearly having as low as possible mains coupling capacitance will be good; so we need a PSU that has a low interwinding transformer capacitance - and guess what, the lowest capacitance are found on those awful SMPS - those pesky small mickey mouse things that audiophiles think are poor.
Also - the capacitive problem only applies at RF, and guess what - you can use RF filters to further isolate the effects of the coupling capacitance - I have proven this via SPICE modelling, an RF PSU filter can be made to isolate the capacitive coupling to ensure that the mains loop is broken - no RF current can flow via this loop. and Qutest is full of RF filters to isolate the RF and capacitive coupling from the mains.
To get rid of RF you must have effective RF filtering, and that means a complex multistage filter. But even simple SMPS filters are better than no filters that are often in linear PSU's.
The hard bright sound is characteristic of more random RF noise entering your system, creating more noise floor modulation, which makes it sound brighter, and if bad, harder and grainy.

But if you are worried about the mains loop then a simple way is to use a USB battery power pack. That will completely eliminate the issue, as it's totally isolated from the mains. My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery - but that was with my setup so YMMV.

The one I use is Poweradd Pilot Pro2. Now this has internal regulators - so it is noisy on the OP - but the key is the absence of mains bourne RF noise. With Hugo 2, adding the unit makes no difference to the SQ, and it's the issue of RF noise that is key, not the noise on the OP. Also, it's completely isolated from the mains, so no ground loops or leakage current is possible.

Like I said, I don’t even fully understand most of this. And in other posts, Rob Watts has acknowledged that in some systems, the high-impedance leakage current ground loop noise can play a role in the sound. 

So my take is that obviously, with a linear power supply for Qutest, you’re going to get less high-impedance leakage current ground loop noise in your system if it’s in other components’ PSUs. So you might like the sound more with LPSU and Qutest in your system because of this. Alternatively, you might just like more RF from the LPSU creating a brighter sound. Or as some have said, there are LPSUs and then there are really good LPSUs that might actually address Rob Watts’ concerns. It would be great if someone with more expertise on LPSUs actually address Rob Watts’ comments instead of a blanket “battery better” or “LPSU better“ or “stock SMPS better”. Otherwise, it just sounds like we are just cheering for our favourite sports teams (not that there is anything wrong with that, I guess).

 

ultraRendu > Peachtree X1 (Toslink) > Chord Hugo M-Scaler > Chord DAVE > Chord Etude > Dynaudio Confidence C1 Signature + Sunfire TS-EQ10 subwoofers

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58 minutes ago, kennyb123 said:

I get the sense also that these guys don’t pay much mind to what Rob says about power supplies as their own experiences tell them that he may have a blind spot there.  Again, I’m not trying to beat up on Rob - he’s a freaking genius.  But he’s human just like the rest of us and that means he’s not omniscient. 
 

 

"The dogma is strong with that one..." 😉

 

There's another well-known and very successful audio company that makes great products but eschews commentary on what we as their consumers, hear or don't hear. Just as well, and yet because of how prominent they are, and because of how their demographic is influenced by them, I wish they would "care" about power and cables as much as the more discerning ears here do. Regrettably, we're all simply human and they have their blind spots as we all do.

 

My dogma: Everything counts in large amounts, and clean power uber alles, and YMMV. 

 

When I try a Qutest someday, it will be with "audiophile-grade" power. Nothing to fear but hearing itself. 😀

Sys Stuff Schiit Yggdrasil A2+SR UEF Black, W4S Remedy/Uptone LPS-1.2, Linn LP12/Hercules II/Ittok/Denon DL-103R, Naim 250 DR, PSB, Elac, Uptone Audio ISO/EtherREGEN, Silnote Audio/ZenWave/Transparent Audio cables 

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4 hours ago, ecwl said:

Wow. I can’t believe this PSU thing is generating so much controversy. I don’t own a Qutest. Half the time, when Rob Watts writes something on Head-Fi, I don’t really understand what he’s saying. Takes re-reading it several times and thinking about it to understand a little more. Moreover, he changes his mind over time. Or he would say, he was expecting other people to use better source components or pre-amp/amp so the problem is not with Chord products/supplied PSUs but he acknowledges that a problem can exist.

 

Going to Head-Fi and reading Rob Watts thoughts, the following is what I got even though I understood like 30% of what he’s saying:

there is no ground with the supplied Qutest PSU; and that is done on purpose, as it eliminates the possibility of ground loops.
for sure ground loops are the major issue, as it's a low impedance direct connection. The problem with a non ground connected PSU is much smaller again, as it is capacitively coupled to the mains and then to ground via the PSU transformer; so here we have the possibility of another loop; but it's capacitive, so only applies with RF signals, not leakage currents in the audio bandwidth. Clearly having as low as possible mains coupling capacitance will be good; so we need a PSU that has a low interwinding transformer capacitance - and guess what, the lowest capacitance are found on those awful SMPS - those pesky small mickey mouse things that audiophiles think are poor.
Also - the capacitive problem only applies at RF, and guess what - you can use RF filters to further isolate the effects of the coupling capacitance - I have proven this via SPICE modelling, an RF PSU filter can be made to isolate the capacitive coupling to ensure that the mains loop is broken - no RF current can flow via this loop. and Qutest is full of RF filters to isolate the RF and capacitive coupling from the mains.
To get rid of RF you must have effective RF filtering, and that means a complex multistage filter. But even simple SMPS filters are better than no filters that are often in linear PSU's.
The hard bright sound is characteristic of more random RF noise entering your system, creating more noise floor modulation, which makes it sound brighter, and if bad, harder and grainy.

But if you are worried about the mains loop then a simple way is to use a USB battery power pack. That will completely eliminate the issue, as it's totally isolated from the mains. My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery - but that was with my setup so YMMV.

The one I use is Poweradd Pilot Pro2. Now this has internal regulators - so it is noisy on the OP - but the key is the absence of mains bourne RF noise. With Hugo 2, adding the unit makes no difference to the SQ, and it's the issue of RF noise that is key, not the noise on the OP. Also, it's completely isolated from the mains, so no ground loops or leakage current is possible.

Like I said, I don’t even fully understand most of this. And in other posts, Rob Watts has acknowledged that in some systems, the high-impedance leakage current ground loop noise can play a role in the sound. 

So my take is that obviously, with a linear power supply for Qutest, you’re going to get less high-impedance leakage current ground loop noise in your system if it’s in other components’ PSUs. So you might like the sound more with LPSU and Qutest in your system because of this. Alternatively, you might just like more RF from the LPSU creating a brighter sound. Or as some have said, there are LPSUs and then there are really good LPSUs that might actually address Rob Watts’ concerns. It would be great if someone with more expertise on LPSUs actually address Rob Watts’ comments instead of a blanket “battery better” or “LPSU better“ or “stock SMPS better”. Otherwise, it just sounds like we are just cheering for our favourite sports teams (not that there is anything wrong with that, I guess).

 

Interesting comment about the Qutest earthing. My 2Qute has a grounding post and the MCRU linear power supply that I use with it, comes with a DC lead that has an earthing fly lead, and so I connect that to the grounding post. I assume the Qutest doesn’t have an grounding post.

System (i): (Stack Audio Link/MoOde > 2Qute+MCRU psu; Gyrodec/SME V/Ortofon 2M Black/EAT E-Glo Petit/Magnum Dynalab FT101A) > Glow Amp One > Klipsch RP-600M

System (ii): iUSB3.0 Nano/Allo USB Signature/MoOde > Bel Canto uLink+AQVOX psu > Chord Hugo > (Tandy LX5; JBL LSR305 ; Audeze LCD-3)

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Qutest is designed to be left floating (RE power supply), this can still be achieved through an appropriately designed linear power supply.  In this case it will still be grounded, eventually, by whatever the RCA outputs connect to.  My understanding is that Qutest has an isolated USB input, so there should not be any worries about a loop as the only ground will be via the RCA return/shield connection.

ROON: DSD 256-Sonore opticalModule-Signature Rendu optical--Bricasti M3 DAC--DIY Purifi Amplifier-Focus Audio FS888-JL E 112 sub-Nordost Tyr USB, DIY AC, Iconoclast XLR & speaker cables, Synergistic Orange Fuses, Dark Matter system clarifiers.                                                       

                                                                                           SONORE computer audio

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