A newbie here and I am running my headfi chain as follow:
QNAP TS-473A as Roon Core and Music Server → Router → HiFi Rose RS250 as streamer → USB → Stingxer SU-6 as DDC and reclocker → IIS → Rockna Wavelight DAC → Fostex HP-V8 Headphone Amp
Am I able to run the HQ Player without adding any PC in my chain? Say, can I run HQ Player in the QNAP server and control it via Roon Remote?
Not really. There are examples of HQPlayer being run on low powered devices as an embedded version but it kind of defeats the merits of the software. And while you could potentially do this on something like a Qnap server I cannot imagine the results would be great. You need an additional PC and the more powerful the better.
I am going to just say “No, not worth your time”. HQPlayer is built with a goal of using powerful CPU AND GPU processors to calculate very math heavy filters in real-time. Any of the filters/modulators you read people on the forums praising would not work on the NAS.
There are DACs that show improved measured performance when you feed them PCM 705/768kHz
Which can be achieved with low powered computers
Can’t really generalise.
But I wasn’t generalising. If I wanted to do heavy stuff HQPlayer would be my first stop. For lightweight stuff I can probably get that done without having to pay out for a licence. I’m not against HQPlayer, I just don’t see much point on a Celeron processor.
You are saying that a Celeron processor “defeats the merits of the software”
Which is wrong if the processor and software combo can upsample to PCM 705/768 and the result is a measured improvement in DAC output - which is the case in several DACs.
There seems to be a thinking that HQPlayer is only worth it for upsampling to DSD (needs more than a Celeron) and this is wrong
Also relatively easy and relatively cost efficient approach to do most of the best algorithms is to use Mac Mini M1 for running HQPlayer. It is also pretty quiet and small at the same time.
I can attest to the success of using the Mac Mini M1. I have it feeding a Holo Spring 3 KTE with DSD512 using Sinc-S AMSDM7 512+fs without hiccups. Of course, I am not using it for anything else. I am also using a Jcat USB enhancer.
You may be better off feeding it DSD256 and using ASDM7ECv2.
You then also might able to use sinc-L Ls Lm Ll Mx xla all the dash -2s… 
Really? I can try that. I am assuming you have heard the differences, then.
I keep changing filters so often I don’t remember what’s what anymore.
On a Spring I believe the details from ASDM7ECv2 would be heard and would probably be preferable over AMSDM7 512fs at 512. But it comes down to preference.
I like seeing 512 light up but it doesn’t always sound better. 