[Pinch]

Give that man a coconut! I think it must have something to do with this:
 

   
Does the AQVox separate the ground from the computer and AP2? Like you said, the PP part powers only the output section and clocks, but the receiver still relies on bus power. The AP2 unit supposedly provides galvanic isolation, but how well such a small unit could do that I'm unsure of. Does driving the SOtM with battery isolate the the power rails only, or does it lift the ground internally from the rest of the computer? (I don't think it should be able to do this.) If the the AQVox is doing something to provide another solid ground between the two devices or completely disconnecting the grounds then it may be able to remove some noise from the system.

 
Reason: I was surprised this morning to hear - whilst no music was playing - a little bit of mains/mobo noise coming out of my speakers - inaudible from the main listening position, but there nonetheless. I had thought that I'd resolved these issues a long time ago, so I was a little perplexed. Then I remembered that, once again, I had unplugged the AQVOX. I plugged it back in, and voila, the speakers were silent. I suspect, then, that there may be something to the idea that the AQVOX is, as you say, either providing a solid ground between the two devices, or completely disconnecting them. Either way, I guess it may end staying.

 

[Gintaras]

Thanks, I might buy and try Aqvox psu unit out of curiousity then, sounds interesting.

 

[BodieBill]

I have now been burning in the AP2+PP for 4 days. The special qualities of the AP2+PP were immediately apparent. Depth, detail. There was a wow there.
However: from the start, and until recently, I was bothered by some graininess in the middle-high frequencies. I tried to enable 'bit 28' on the AP2 which seemed a slight improvement, but not solved it.
Then I experimented with the Audirvana settings. To my surprise, disabling integer mode solved the problem. Graininess gone.
So now I use Audirvana direct mode but NO integer mode.
Anyone had this experience?

 

[Gintaras]

I have now been burning in the AP2+PP for 4 days. The special qualities of the AP2+PP were immediately apparent. Depth, detail. There was a wow there.
However: from the start, and until recently, I was bothered by some graininess in the middle-high frequencies. I tried to enable 'bit 28' on the AP2 which seemed a slight improvement, but not solved it.
Then I experimented with the Audirvana settings. To my surprise, disabling integer mode solved the problem. Graininess gone.
So now I use Audirvana direct mode but NO integer mode.
Anyone had this experience?

+1 here

 

[Sanlitun]

This thread is a couple of years old now and I am wondering if there is still a notable benefit to using an AP2 with DACs that have more modern Xmos USB interfaces?

 

[philo50]

  This thread is a couple of years old now and I am wondering if there is still a notable benefit to using an AP2 with DACs that have more modern Xmos USB interfaces?

IMO yes, but only when used with the Pure Power....

 

[KmanChu]

  This thread is a couple of years old now and I am wondering if there is still a notable benefit to using an AP2 with DACs that have more modern Xmos USB interfaces?

It seems like most DACs still benefit from a really good source. The Xmos is a good place to start but does not guarantee a good implementation. The effect on newer devices with true asynchronous performance may be due to the electrical isolation the separate converter unit provides (as the previous post alluded to the PurePower option often brings the biggest improvement.)

 

[drez]

  It seems like most DACs still benefit from a really good source. The Xmos is a good place to start but does not guarantee a good implementation. The effect on newer devices with true asynchronous performance may be due to the electrical isolation the separate converter unit provides (as the previous post alluded to the PurePower option often brings the biggest improvement.)

 
So true, apparently AP with purepower measures the same jitter as without, yet it sounds miles better.  I tend to forget this from time to time.

 

[project86]

  This thread is a couple of years old now and I am wondering if there is still a notable benefit to using an AP2 with DACs that have more modern Xmos USB interfaces?

 
I still use AP1+PP as a reference source for all DAC reviews. Much of the time, though not always, this method is superior to the built-in USB. I'd say modern USB inputs are certainly better than a few years back, but still don't keep up with a purpose-built system like the AP. 
 
That said, once you go PurePower you can't run the device without it, so I don't know how well it would stack up without that component. The difference would surely diminish. 

 

[negura]

One work-around is to use a Y-split USB cable and a 5V linear regulated PSU. It granted very significative improvements over the USB powered AP2.
 
With enough gain the effects of dirty power or noisy USB data lines can be heard. Think of a powerful speaker amplifier (obviously if any music was to play it would likely kill the headphones, so careful if you try this @home). Under most conditions, on normal spec gain, while the dirty power is not audible, I found, unsurprisingly, it messes up the sound quality.

 

[KmanChu]

  One work-around is to use a Y-split USB cable and a 5V linear regulated PSU. It granted very significative improvements over the USB powered AP2.
 
With enough gain the effects of dirty power or noisy USB data lines can be heard. Think of a powerful speaker amplifier (obviously if any music was to play it would likely kill the headphones, so careful if you try this @home). Under most conditions, on normal spec gain, while the dirty power is not audible, I found, unsurprisingly, it messes up the sound quality.

 
Not to take the thread off topic but, Negura, how do you like the ifi Gemini with the Yellowtec? I am using a conventional cable from an ifi iUSB Power supply to the Puc2 Lite but was considering trying the dual headed Gemini. Have you compared the Gemini to other dual headed options with the Yellowtec?

 

[negura]

   
Not to take the thread off topic but, Negura, how do you like the ifi Gemini with the Yellowtec? I am using a conventional cable from an ifi iUSB Power supply to the Puc2 Lite but was considering trying the dual headed Gemini. Have you compared the Gemini to other dual headed options with the Yellowtec?

 
I did not have any other Y cables to compare it with, except for a DIY silver cable, but that's hardly relevant to anyone but me. I have only compared it with "normal" USB cables. But I am pleased with it. The signature is neutral with very good detail.
 
The weakness of IFI IUSB is the cheap switching wall wart it comes with. When I realized I was going to need a linear regulated PSU, I decided to switch to an Y split cable + linear reg PSU as it doesn't require an additional USB cable... Anyway although I have spent a lot of time with interfaces/cables/power solutions, I feel I just began to scratch the surface to what various combos offer.

 

[KmanChu]

   
I did not have any other Y cables to compare it with, except for a DIY silver cable, but that's hardly relevant to anyone but me. I have only compared it with "normal" USB cables. But I am pleased with it. The signature is neutral with very good detail.
 
The weakness of IFI IUSB is the cheap switching wall wart it comes with. When I realized I was going to need a linear regulated PSU, I decided to switch to an Y split cable + linear reg PSU as it doesn't require an additional USB cable... Anyway although I have spent a lot of time with interfaces/cables/power solutions, I feel I just began to scratch the surface to what various combos offer.

 
I was skeptical at first but am now a believer. iFi is fairly proud of their wall-wart and claim to have custom designed it. They claim that between their custom wart, use of a good regulator and filtration they have a very quiet unit.  A good switching supply shouldn't be discounted offhand. I believe Linn uses custom switching supplies in all of their digital sources. At any rate, I've now gone off topic, but just thought I'd stick up for the iUSB.

 

[Sanlitun]

My AP2 was just delivered, and thankfully on a Friday so I will have a little time to play with it over the weekend. My unit has firmware 1.30.

 

[Chodi]

  My AP2 was just delivered, and thankfully on a Friday so I will have a little time to play with it over the weekend. My unit has firmware 1.30.

Sorry no help with the driver but I am interested to know the improvement you find with your AP2. I just can't get over the concept of paying half the price of your dac for a new usb connection when there is already one built into the dac. I am really interested to know if you feel it was worth it?