I have written a short review in Italian and English of the Holo Audio Spring level 1 RED at www.audio-linux.com Direct link: http://tophifi.it/html/holo.html   The review is focused on what I think it is the best method of upsampling the signal.

An information. How XMOS USB interface is powered? Internal or from cable?

I would like some information on the output analogue stage of iFi micro with setting DIRECT, BitPerfect/extreme filters and RCA output:   1) In this case I understand that the filter is analogue (not digital) but...is also passive? If not, it is made with discrete components or with a chip?  ...

With my Sony Z Ultra with Android 4.4.4 only USB Player Pro is working (both PCM and DSD). Spotify and Neutron are not working.   However, for what I know, this is NOT a limitation of this Android version or this smartphone, since USB output is working fine with all applications using...

I have made some tests driving micro in BitPerfect mode and polynomial upsampling to 768K (polynomial really is not a filter, I would call it "higher frequency digital reconstruction of digital signal"). I have tested also with HQplayer DSD to DSD256 or PCM to DSD256 options. With this...

Yes I know that it is possible. Only on linux DSD512 was not possible until now.

Yest BitPerfect is the noisiest but probably is the best for impulse response (and this is very important for audio quality).   Personally in this case I think the best is upsampling to the highest possible value (possibly with a polynomial function, that will preserve impulse response)

For linux DSD DoP: the DSD signal is encapsulated in a PCM container, but not converted to PCM. In this case iDSD can play only up to DSD256.  DSD native: the DSD signal is sent as it is to the DAC. iDSD can play up to DSD512   For Mac, I think that playing up to DSD256 is possible. Enabling...

Some interesting news. Now DSD native (non DoP) support up to DSD512 is possible in linux from next kernel 3.18.x and alsa 1.0.29. It is possible to try this compiling new kernel with the patches at the link below and alsa-git. To test it you must compile last version of mpd-dsd.   I have...

I have fixed the problems connecting the micro directly to USB 3.0 output!

I know that this has been discussed a lot, but I would like to know the exact sequence for enabling battery power.  For example, is this correct?   1) switch on iDSD 2) switch on computer After listening: 3) switch off computer 4) switch off iDSD --> usb charching from computer   Is iDSD...

Perfect! My iDSD will always be connected to USB and my Metrum Octave is 24/192.   What I would like to know also is if the analogue output of micro iDSD is disconnected when spdif output is connected to external DAC. Or is it capable of playing at the same time from spdif output using...

I have just ordered the Micro iDSD. I would like to connect my Metrum Octave DAC to digital output and use iDSD mainly for DSD.   Do you have some experiences with s-pdif output? Do you think that I could expect the same quality about jitter for example? Or s-pdif encoding could make it worse?

I have already asked. The answer was: "so far we have not tested anything related to Dolby/DTS, so I cannot give you any useful info at this moment. "

Since I could use Hydra X+  on BNC output for my hifi system and on coax output for my AV receiver, I would like to know if it will pass or not Dolby and DTS signals for decoding in the receiver.