Don't have a USB isolator. Could lift the power ground of the Topping, but it will still be grounded eventually through the output signal connectors and amplifier power grounds (although amps are powered through common mode chokes inside a power conditioner). PC is a laptop. Suppose I could run it on battery for awhile. Don't normally find it makes much difference here, as the PC is also powered through a good quality power conditioner. It makes much more difference not to let Windows Sound Engine resample the audio stream.
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I am sure that the spirits of the Flat Earthers from centuries ago (having died before the truth be known) are about to rise up after I say this, but all manner of variant grounding/isolation/filtering can influence the results, even the USB isolators can't all be trusted to transmit data without corruption.
My amplifiers have the ability of ground lifting, being switched into that position as it sounds better. In previous testing a resistor in the several hundred KOhm value was connected between the chassis and earth ground, being of sonic virtue dependant on the manner other devices where connected. Grounding isn't straight forward. I have also found that operating the laptop on batteries makes a difference, but not enough yet to keep doing so in my system.
I own an Elgar Power Line Conditioner. It produces and output that actually looks like a sine wave with 2pF coupling capacitance between input to output. It is designed for research applications involving highly sensitive physical measurements. Although capable of providing reasonably high currents it isn't considered enough as not to influence the sonics of at least the power amplifiers involved. This also suggests that others would require the purchase of such devices to achieve the sonics being described.
It seems best for Markw4 and the others involved to just "do it" without being overly bogged down with the details.
The Monster HTPS 7000 MkII power conditioners here are quite good for audio. They were designed by our own Richard Marsh and by Demian Martin (@1audio). It was the best thing on the market back in the day of hi-fi stores, and is still quite good. A friend uses a PS Audio Regenerator and thinks its a little better. The ones I have are still quite good by any standard. The improvement in SQ can be quite striking. In fact, Richard secretly installed one in the listening room system that Stereophile used to have back in those days. Soon as they played some music they asked him, okay, what did he do to the system? Anyway they as important as RF shielding is here. The custom dacs, AK4499 and DAC_Lite are both in steel file server cases for shielding purposes.
Regarding USB isolation, although I use (sometimes externally clocked) I2SoverUSB boards which include galvanic isolation, I have also compared sound with externally clocked Amanero boards running from clean 5v power. USB ground from the laptop is still intact with the dac in that case. No audible difference here. at least not with that PC, and not with the power conditioners I use. Really, I check a lot of things whether or not other people imagine I might forget to check.
Regarding USB isolation, although I use (sometimes externally clocked) I2SoverUSB boards which include galvanic isolation, I have also compared sound with externally clocked Amanero boards running from clean 5v power. USB ground from the laptop is still intact with the dac in that case. No audible difference here. at least not with that PC, and not with the power conditioners I use. Really, I check a lot of things whether or not other people imagine I might forget to check.
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It was a simple question. How was your listening comparison conducted that resulted in 2 DACs sounding different without any doubt? Based on other forum posters reporting the same type of results, likely your listening comparison was same as theirs, no bias control, no level matching, no aural memory span compensation. It's not against forum rule to post such results. I've done such comparison too.
You should try a listening comparison with bias control, level matched and aural memory span compensated (quick switching between components). If that's too much work for you, at least you can read about tests like that on DACs.
I once compared a standard IEC cable with one priced at I believe >$2,000 in an audio store demonstration. This was connected between some Moon gear and a power line conditioner that I can't remember the name of. The difference was striking. I am keeping this a secret because if revealed my credibility in the DIY community would tank... OOPS!
That has been the question which you refused to face. Not surprising since you've been posting for business mission.
Evenharmonics, when without argument in your favor, you are without any proof sowing suspicion on motives of opposing members. This is not only very inappropriate, it’s outright nasty. Please, point out one post where Jakob2 promotes products of some company in audio business. All I can find is competent discussion on various audio related topics.
Your obsessive following of Markw4 to any thread where he posts any opinion on sound quality (how dares he without scientific proof?) and endless parroting of the same “questions”, contributes less than zero to the quality of discussion. In fact, it ruins every thread where you appear.
Yup, that’s my opinion which I’m entitled to without scientific, peer reviewed, analysis of your posts as a proof.
I explained once, why my subconsciousness automatically, against my will, reads your nick as Evilharmonics.
Please, change your approach to discussion.
Your obsessive following of Markw4 to any thread where he posts any opinion on sound quality (how dares he without scientific proof?) and endless parroting of the same “questions”, contributes less than zero to the quality of discussion. In fact, it ruins every thread where you appear.
Yup, that’s my opinion which I’m entitled to without scientific, peer reviewed, analysis of your posts as a proof.
I explained once, why my subconsciousness automatically, against my will, reads your nick as Evilharmonics.
Please, change your approach to discussion.
Better way for you to approach this is to create your own forum so that you can control how the forum members post.
Please direct comments and questions to the mod team via PM or the help desk. This is covered in the Rules.Forum requests and features can be discussed in the sections provided for those.
https://www.diyaudio.com/community/forums/new-platform-issues.191/
Elgar made both active conditioners and ultra isolation transformers. From your description you have an isolation transformer. I remember those to have some mechanical hum. its unlikely you would use the active conditioner since those sound like turboprops warming up for takeoff.
The HTPS7000 is similar to the ultra-isolation transformer, except it has two transformers, additional filtering and the option of 'balanced" or isolated power. There is no way to predict which would be better.
The Elgar is the 6000B as a 1KW active conditioner, that in the reading it has 1pF input/output coupling. This is an incredible figure to reject common mode. I disconnected the fan because the load was so low the current meter barely moved off zero. The active unit also has excessive mechanical hum and would need to be moved outside the room to use it. I haven't tried it for a long time... though it would be interesting to test it again with some later gear.
Read this -> https://sound-au.com/earthing.htm
If you wish to defeat the ground of your amp, (or anything for that matter) point 9 is the way to do it safely, my only recommendation is use a 100 ohm R instead of 10.
I've lost count of the number of pieces of expensive hi end gear I've worked on that required rectification (no pun) of dangerous grounding practices.
TCD
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