Good HQPlayer configuration for Holo Spring 2 KTE?

I own a Spring 2 KTE fed by a Pi2AES running Ropieee, with 2x upsampling of 44.1k and 48k material via Roon (linear, slow rolloff). I’m considering different upsampling possibilities to see if I can get even more out of this excellent DAC. Pi2AES is very nice for what it does, but limited to maximum 192k PCM. Quality is more important than price, but I don’t go for silly gold-plated digital gear with vague magical claims. In addition, the house’s open physical layout is not conducive to having noisy servers anywhere; my Roon server is a fanless Zotac CI662 nano. I don’t do Windows, only Linux or macOS. The questions:

  1. What to use to run HQPlayer?
  2. Roon endpoint for Spring 2?


Hi, Fernando - You may want to seek the advice of a YouTube reviewer, GoldenSound. He has the Holo May KTE, is familiar with HQ Player, and also uses Roon.

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i9-10900K or KS (coming soon?) inside a big Fractal Design case with big Noctua fan.

Or newest Apple Silicone Macs are good. Next Mac Mini should be even better than current.

RPi4 running Jussi’s custom NAA image works really well as endpoint :


Agree with @dabassgoesboomboom but would also suggest AMD Ryzen 5 5600x, see comparison here. The 65W TDP compared to 125W should enable a Noctua fan to cool it very quietly. The 6 cores v 10 cores aren’t going to matter for HQP.

The i9 10900K has better turbo single core performance (5.3 v 4.6) but I’m not sure that is going to translate into increased options in HQP.

To go beyond the particular questions, try

DSD 256 Output in HQP;
ASDM7EC Modulator;
Ext 2 Filter.

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It may help for doing other stuff at the same time as HQPlayer?

Like running Roon on same machine?

A bit of headroom

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With 6 cores I can’t see it having an issue running Roon with HQP.

But better single core performance is certainly desirable for the EC mods, and even if it doesn’t currently enable more options, Jussi is continuing to introduce filters. The higher single core speed might enable increased ext3 options, I can’t say.

So it’s the usual balancing act between price, TDP and performance. I can’t recommend one over the other without doing the real world comparison.

Thank you for all the suggestions so far, lots to think about.

Having multiple cores helps on heavier filters like ext3 and gauss-xl(a).

Or filters like sinc-Mx and sinc-L for which, when used with EC modulators, 10 or more cores would be optimal for stereo output. As long as the clock frequencies don’t suffer too much!

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Getting back to this question (was busy with other stuff during the summer): would a current Mac Mini M1 be a capable choice (as @dabassgoesboomboom hints)? I like the form factor, I’ve been using Macs for decades, and the M1’s vector capabilities seem just right for convolutions and other DSP operations, assuming HQPlayer can take advantage of them. I’m leaning towards setting a headless M1 just for HQPlayer, and a Pi 4 with the custom NAA image driving the Spring via USB.

It’s not my hint, search the forum for M1 by Jussi and you see posts like:

But we should have an update on the below in the next month or two:

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Hi @jussi_laako

What’s the difference between Holo Spring2 and Spring3, in how USB interface is powered?

I saw this post on CA Forum: “with Spring 3 when the DAC is in standby mode, USB interface disappears. This wasn’t the case on Spring 1 and Spring 2.”

So Spring3’s USB interface is entirely powered by the USB source?

But Spring2 USB interface was powered internally?

Spring2 USB input was galvanically isolated like Spring3 is?

No, it is powered from the DAC itself. So it is affected by DAC’s standby mode.

Could be, or could be from the USB. But Spring 1 and Spring 2 also keep more things powered up in standby mode (including display). They also consume more power in standby you can notice from the chassis temperature.

Yes, I think my Spring 2 and Spring 3 have essentially the same USB interface.

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Interesting, I wonder how they can power the USB section but keep galvanically isolated ground.

I guess using DC to DC convert like my Intona 5kV isolator uses.

Intona can only provide approx 100mA of isolated power.

But I guess in Holo Spring 3, 100mA is more than enough to power the USB source side of the isolation , just for USB handshake I imagine.

It’s clever design by Holo but I guess same thing is achieved by adding an Intona 5kV to my ADI-2 (AKM)

Yes, that’s the thing… You have a mains transformer though, but still.

Intona has switching regulator going through isolating pulse transformer and then through linear regulation.

Could be, I can check with mine.

In a bit different way yes. Main difference being different isolation point. Holo isolates I2S between the USB interface and DAC. While Intona isolates USB link.

But this shouldn’t be too much problem, because ADI-2 doesn’t suffer from the typical XMOS problems - because it doesn’t use XMOS.

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Ideally you want both :grinning: - isolate USB input from rest of DAC and isolate digital section from analogue.

Ted Smith’s upcoming ‘Signature’ DAC will do something like this, with a 2 box solution.

Each box with independent AC power.

Box 1 has all the digital inputs and all DSP. And has fiber optical output to Box 2.

Box 2 converts fiber optic signal to analogue.

Some DACs out there (like Lumin) have SFP input but they also have the computer inside the same box as the analogue electronics. And share same PSU.

Playback Designs have been doing 2 box solution with optical link for years but still had the FPGA in same analogue box.

So Ted Smith’s idea is quite different.

Revisiting this question: I have a May KTE with a hefty Intel i9-11900 server running Embedded, streaming NAA to a UP Gateway, USB via Intona to May. I’m really happy with what I’m getting there. I’m now totally sold on HQPlayer DSP for Holo DACs, so I also want to get the best of the Spring 2 KTE in our vacation place. From the thread above, I’m not sure I can get the same amazing performance using USB, so I’m looking for alternatives for the NAA endpoint connecting to the DAC. I’d be running a second Embedded instance on some not-too-noisy server squirreled away in a closet. I’m time-constrained so something pre-assembled would be best, and ideally not as bulky as the (otherwise excellent) Silent PC MusicMaker 2U I have in our city place.

Something like that would likely work fine, especially if you like to run at DSD256 instead of DSD512. I have one machine doing even DSD512 (ASDM7ECv2, using HQPlayer Embedded) with i5-11600, but it is on the edge for that one. Maybe someone has tried similar with i7-11700 or i9-11900 and can comment on success.

Why can’t you do the exact same as your current machine (11900)?

With an UpBoard NAA (like you are already doing with Holo May) why won’t it work with your Spring 2 ?

But as Jussi said, run at DSD256

For the server, the one I have in our city place is fine, but is bulky and relatively expensive. For the endpoint, the Spring 2 USB input is not at the same level as the May’s, so I2S might be a better choice. I guess I could get another UpBoard with a USB>I2S bridge.

Ah ok. I didn’t know you meant the quiet 11900 is bulky.

You should see my 11900K - that is bulky !

I’m pretty sure the Spring2 USB input is just fine. I haven’t seen any objective thing to show otherwise. Jussi has shared Spring2 USB input measurements over on Computer Audiophile forum a long time ago - it is very very good.

It’s USB input is already galvanically isolated but you can add an Intona (like you do with May) before it for peace of mind.

I would just replicate what you already have feeding May !

Quiet 11900, UpBoard NAA OS (fanless and silent) and optional Intona.

I’m pretty sure people preferring I2S inputs are preferring something technically worse than USB - which is fine because personal preference is ok in life!

I2S definitely cannot be technically better than USB unless there is a shockingly bad USB input design/implementation (not the case with any Holos).