Buying the iPurifier thing ........

My question on iFi’s Purifier:

Given I have a RPI-3 (USB Out) and I have a DigiOne as well … if I now wanted to feed a DAC and were to buy (only) one of those Purifier’s … which one the USB or the SPDIF version should I try in terms of SQ only… or doesn’t matter so much, because both work the same way and only differs the output plug?

My take on this (as I don’t have the same situation and devices, it is not based on real experience. Its more educated guesses):

First, the DAC.

If it can be a master DAC than feeding it from a slave device would make sense under the assumption that the DACs implementation has the best masterclock of all.

SPDIF only works if the DAC is in slave mode, so that leaves only USB in the given choices. No real need to do reclocking on USB level as the signal only is a slave signal. But cleaning the signal (on electrical level) can be beneficial to the SQ of the DAC as the DAC receives a signal with minimal polution/interference. Here the USB iPurifier can be a good option.

If the DAC can only be a slave (or does not have a superior masterclock implementation), feeding over SPDIF or USB are both options.

The DigiOne claims to be the best SPDIF transport available taking care of a proper clocking and clean signal. Assuming it is true, and so far reviews claim it is, no need for adding a SPDIF reclocker.

For USB on the otherhand, the Pi(-3) is known for its ‘bad’ USB signal. Both clocking wise and electronically. Here the iPurifier is even a bigger SQ upgrade as it works on both the timing and signal polution.

So, my suggestion: get the USB iPurifier and compare it against the DigiOne and if possible try both Master and Slave mode of the DAC.

As always, just my 2 cents and YMMV.

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Thanks Patrick, thats quite revealing to me!

Actually my DAC is a AQVOX USB and has a Master Clock function (that can be switched off), if I took it right from the papers where it says:

192kHz/24bit Upsampling
All incoming digital signals are being resampled to
192kHz/24bit and reclocked by a high-precision
master clock (function can be switched off). After the
“Upsampling” the signal is passivelz filtered and
@downsampled@ to the original value. Upsampling
allows the application of a noise shaping filter with a
threshold far beyond human hearing. Furthermore
the reclocking circuit reduces digital jitter to a
minimum. Despite the high quality of this upsamplersolution,
AQVOX does not recommend to use it for
high-quality sources. For HighEnd sources the bypass
switch should be enabled. Sources below

This DAC is a design dated 2009 but it has certain reputation and 2x PCM1796 and so on blablabla … so I think I will try then the USB Purifier. I did not really compare yet vs the ALLO Boss in a critical listening but in a session “quick & dirty” I noticed it is still one step ahead vs Allo Boss in terms of clarity and refinement, specially when playing classic tracks. But not really way ahead on the other side… so thanks for your comments again!!

You are welcome :slight_smile:

I did a quick google on your DAC and assuming you have the MkII version, it indeed makes sense to stick with your DAC instead of a HAT DAC like the Boss.

The upsampling/oversampling is a nice feature but as the vendor recommends, for high quality sources it should be turned off. Also if the specs are accurate, the USB interface only allows a maximum of 48/16 as input resolution.

On the coaxial SPDIF the maximum is 192/24 which is much better if you have quality source material in high-res (like Qobuz offers very good hi-res classical music).

As you mention that you have a DigiOne, I would use that. Get a quality cable and I think you can reach a higher SQ level with the right source material then going the USB route.

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Oh, maybe also worth mentioning. If you use the standard powersupply for your Pi, maybe consider an upgrade for it like the iFi iPower, Sbooster or something simular. In some setups, a better PSU for the Pi can be beneficial for the SQ of the system (has to do with things like powerline polution and interference/radation).

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