iFi DAC upgrade with MQA Tech Note

(Chris ) #1

Tech people may find this iFi Tech note interesting.

(Sean) #2

I don’t really have any strong feelings but here is a great post by @jussi_laako also:

"looked from two extremes, both Chord talking about transient accuracy with extremely long filters and MQA talking about transient accuracy with extremely short filters are both right in a way, but only looking at things from one point of view while ignoring others. As usual in life, truth is somewhere between the extremes…"


I have the new iFi Pro iDSD by the way and have had Chord DACs - all sound fantastic.

And in the big picture, we shouldn’t forget there are other things that influence the sound/performance of a DAC, like the analogue output and power supply section designs. See the below great post from the well respected, late Charles Hansen of Ayre Acoustics:


(Peter Hafkamp) #3

Since the new GTO filter is running on the Xmos chip,does that mean its only available using the USB input of my micro iDSD bl ?

(Nathan Scrivener) #4

In order to get the benefit of this filter, should we be avoiding upsampling in Roon and instead just send the non-oversampled audio straight to the DAC? Or does this not matter?


Yes, GTO filter is a custom designed embedded into XMOS chipset and requires USB input. This new filter is not available in off selves DACs. A closer look at GTO filter resembles to a Minimum Phase sharp roll-off. The only difference is GTO can achieve this by using lesser ‘taps’, this translates to better linearity across the frequency response.


Looks like DSD still have the best overall transient response. Besides, if you like PCM with the best transient response, you can just run it in non-over-sampling mode if your DAC allows it, and you get almost an ideal response. The downside is degraded SNR and aliasing effects.

The solution to all these problems is to use DSD.