dan92075

I think that article was supposed to be a prank. There is no audio organization called AIAA.

I have a Wyred Dac2SE I have tried this experiment on both a 2year old PC laptop and a half year old Macbook Pro running Jriver19 I did comparisons using the free 2L samples: They have DSD64, DSD128, PCM192, etc all converted from the same original DXD file. I felt the DSD64 using pcm2dsd on the fly using the PCM192 sounded pretty much the same as the DSD64 I downloaded from 2L

My preference right now is 24/192 material but played using Jriver pcm2dsd in DSD mode at DSD128

That was my very first impression too - a slight loss of dynamics. However, later what was eye opening for me was when I was able to resolve details in familiar tracks that I had never heard before. I then began to realize that the slight "loss" of dynamics was due to noise riding on top of the peaks. I realized I was used to an extra fizz on the peaks which was giving a fall sense of dynamics. As I began to enjoy the extra detail and texture it now sounds wrong to me when I go back to the noisy case. Let me know if you come to that conclusion to - or if you still think there is loss of dynamics?

Thats Alfe! Hoping it will provide you some benefits. .

To first order, an active filter is an amplifier wrapped up with a passive filter So in essence, with an active filter you effectively have another amplifier in your chain prior to the power amp. So similar to how a preamplifier can have degradations including noise figure, distortion, transit time distortion, etc - the active filter will have all the degradations that a preamp would have (and actually probably worse) Perhaps this may explain why emailtim saw better performance with the Bryston 10B Sub PRO removed from the signal chain?

Thanks Alfe - yes no possibility was a bit strong of a statement - but I guess if all other processing is successful on a computer - your word processing is not getting corrupted - your video processing is not losing pixels - then its highly unlikely that the audio processing is losing bits. Anything is possible though As far as the AQVOX LPSU - I see its only works on USB power. Did you ever have a chance to try out an iFi? I am asking because iFi regenerates/isolates any noise on the digital lines as well, and in addition can also isolate ground. It would be interesting to see if you use an iFi if you could have an additional improvement?

Thanks for your comments, alfe. What kind of USB are you using the 5V LPSU with? Is it an iFi or a SOTM card? As far as theory - in a strict sense, the computer processing is all digital and analog noise is completely irrelevant to the digital signals - there is no possibility of corruption on that front So its fascinating you are hearing significant improvements - I am wondering if its due to ground loops from the SMPS making its way through the USB ground, or maybe the SMPS noise is going into the power grid, or maybe the big inductor in the SMPS is magnetically coupling to the big inductor in your DAC if they are in close proximity? Sorry - I am an engineer - so I always drive myself nuts trying to understand things to the last detail! But thank you very much for you input on this - by the way - what linear PSU did you end up using?

Yes, I am very curious to hear Tranz's opinions on this topic as well since he has done so many experiments in this area. . . Dan

Sorry for not being clear - when I said preamp I did not mean volume control, I meant its not a passive device, its uses active amplifiers pre the PA?

Depends on your local dealer. My dealer actually offered me to try out a demo unit first. But given it was only $200 bucks, has very good reviews everywhere, I decided to go for it and just purchased one!

I have the same experience as Kelly. I am using a Wireworld Platinum USB cable from DAC to iUSB. And from iUSB to Touch I am just using the short blue cable enclosed. The improvements were quite significant as described earlier. And a good sign, is it never even dawned on me that I could possibly further improve by replacing the short blue cable Again, the increased micro-detail is so much improved I would be really surprised if the short blue cable was somehow limiting performance - - also it is very short after all so even if the impedance was a bit off it should not make that big of an impact. . . so I would not sweat updating the blue cable

Hi Tranz, Are you using Async USB? I saw a writeup on the IFi by Darko - he claims that with Async USB combined with the iFi iUSB, one can use an unmodified Mac Mini and get top performance As far as I know, there are 5 possible noise corruption mechanisms that I am aware of: 1) The USB clock 2) Noise injected through the USB power lines 3) Ground loops along USB 4) USB bit corruption 5) computer noise injected into your power grid, and getting into the preamp, DAC, etc Some solutions for these are the following: 1) Let DAC do its own clock by using Async USB 2) use a device like iUSB to clean up USB power use a shielded/filtering, or two-cable USB cable use a DAC with galvanic isolation just making these numbers up, but lets say iUSB provides 40dB isolation, filtering USB cable provides 10dB, and galvanic isolation provides 30dB - - in total there should be more than enough isolation 3) iuSB allows one to lift ground also, a DAC with galvanic isolation 4) Is USB Bit corruption possible due to switcher noise? Skeptical - one thing to point to is processor would start to quickly choke if bits were getting transferred around with corruption. . 5) Use a filter, use power outlet on another grid, etc It seems that Async USB, iFi iUSB, and galvanic isolation in DAC are the key things in all this. Its not clear to me why any of the other changes are necessary beyond this? (I am open to being educated if I am missing something)

Just checked - my model is a microUXXXXX Yet I still am not able to power of my Touch - I have the exactly the same symptoms you have At the end of the day, I purchased it specifically to clean up the USB - and it fullfills its mission in that regard brilliantly for its low cost - - so I am a happy customer!

Nope - my Touch begins to boot up with iFi power but then when just about done it turns off. . .