Reclockers and DACs

[nic]

Hello ,
I've just picked up a Pi3 and now considering an upgrade to the old Pi1 / IQAudio PiDac . I would like to use a reclocker in conjunction with a DAC that's compatible with Rune first and foremost . I would also like to consider a more exotic DAC which has the ability to be hacked for a direct analogue breakout for a valve output stage rather than use , say ES9023 or PCM5122 based-DACs with charge pump power supply and inbuilt op-amps .

Suggestions please Allo stuff looks the most interesting so far

cheers

Nic

[janui]

Hello Nic,
Some food for thought…
Before you spend time and money on a valve solution you should look at this http://sound.whsites.net/valves/myths.html and for more details this http://sound.whsites.net/valves/index.html.
There are affordable valve DAC's on eBay, these are generally USB DAC's. The AK4490EQ DAC chip is popular with USB DAC's, while the I2S DAC's tend to use the ES90xx or PCM51x2 chip's. What I see from other internet posts concerning valve equipment is that people tend to buy a ready built product then then take it apart and rebuild it. It seems to be a very personal process and if you take into account Rod Elliott’s views, something which takes great skill. After considering this I gave up on the valve idea.
But I am looking at reclocking techniques (the I2S route), the Kali i2s Reclocker seems to be the DIY standard at the moment. But before I buy this reclocker (and compatible Allo DAC) I am planning to build a sort of asynchronous reclocker/buffer/oversampeler. This is just to see if it has any effect on the performance of ES90xx or PCM51x2 DAC's. The idea is based on an old post here http://diyparadise.com/w/?s=reclocker, no idea if it will give any sound improvements. I will post the results in the DIY section.
The other route which I am considering is using a hifiberry dac+ pro. This DAC uses a PCM5122 DAC which works in synchronous mode using one of the two on-board switchable clocks. This is partially what Kali i2s Reclocker does (but without the buffered I/O). There are other posts on the forum concerning this DAC, some people have had difficulties. It’s on my Christmas presents list
I currently use a hifiberry dac+ in my main system, this is basically the same as your IQAudio PiDac (PCM5122 chip). My experiments with other low-cost DAC solutions have not yet been able to improve on the sound quality.
Janui

[nic]

So far I have tried :

DIYinHK XMOS USB / ES9023 DAC (battery powered)
Original Hifiberry (software volume control only)
IQAudio PiDac

The PiDac sounds the better of the two I2S DACs , I had a few issues with crackling and drops with the USB setup which I have only used with the early releases of Rune . The Hifiberry pro looks interesting but you are limited to the onboard crystal quality and stuck with the onboard DAC

I have a Kali/Piano on order , was considering the Soekris but with the Kali , there should be some flexibility for use with other I2S DACs which can run in slave mode . I have read nothing but positive reviews so far so have high hopes .

As for valve output stages , I do ground up designs . I'm not into these ECCxx based DACs or funny little Ebay doo-dads . It's easy enough to use a directly heated type such as 4P1L . The 316A pictured in my avatar is another story though , a bit more of a challenge

cheers

Nic