I think it's efficacy depends a lot on the settings / DAC. I never got to try HQP w/ Wavelight, but you might like it a lot w/ May. Yes USB direct to May for me. I think some NAA endpoints can handle 1.536M but most don't go that high.
I'm currently using Zenith 3 as Roon core, pointed to HQP processing on my gaming PC. I daily the PC, often doing stuff simultaneously w/ HQP running so it's not ideal for SQ, plus Windows is inherently is pretty 'noisy' for audio. Even in this less than optimal setup, it sounds better to me than direct from Innuos. So I'm hoping a dedicated Linux solution will bring further improvements.
I originally engaged w/ Pareto Audio but ultimately pivoted to pursuing a DIY build. I also considered a M1 Mac Mini which many are successfully using for HQP. But the custom route seems more flexible and fun for tinkering. AS forum has been a huge resource, I've glanced thru many threads there which helped me gauge components and software. Gathered most of the parts already but a good LPS isn't readily available, either long build times or out of stock (Paul Hynes, Keces, Sean Jacobs, etc.) So I'm still waiting/deciding on the power supply to finish the build.
Getting off-topic for a May thread but here is a list of my parts/comments below, in case it's helpful to anyone curious of doing similar. This is simply what I've gathered in research thus far (not first-hand experience), so I invite anyone more knowledgeable to chime in/correct me as needed.
Case: HDPlex H5 - Fanless passive cooling, HDPlex seems to be the most popular, but other options include Streacom, Turemetal, Akasa, etc.
CPU: i9 9900K - Overkill for PCM but wanted headroom to play with DSD which is more CPU intensive w/ certain modulators. Passive cooling also seems limited to 95W CPUs so that limited my options, a lot of the newer gen CPUs are 100W+.
RAM: Apacer 2x8GB - Many recommend Apacer (low latency industrial RAM) as opposed to consumer RAM so I went w/ that. 2x4GB should be plenty but went w/ 2x8GB for headroom because OS like Audiolinux or Euphony have an option of 'ramroot' which moves playback or even entire boot into RAM to avoid disk interaction completely. Can be finnicky but potentially worth trying for SQ w/ proper config.
Motherboard: Gigabyte Designare Z390 - Some Gigabyte boards have what they call a DAC-UP USB port, supposed to be a clean noise-treated output specifically for DAC use. I'm planning to skip a PCIe USB card like JCAT or Pink Faun (for now) since May's USB is supposed to be quite good as-is. So I went for a board that at least has some focus on motherboard USB output, unsure if it's a complete gimmick or not.
Boot Drive: Intel Optane M10 64GB - Apparently it's all about low latencies which Optanes are known for, so it's good to use as an audio OS. 32GB is enough but again went w/ some headroom just in case.
Storage Drive: Samsung 970 2TB - Not sure if there's much consideration on storage specs, but can't go wrong w/ Samsung SSD.
Software: Euphony - Linux based OS tuned for audio/SQ. Similar to Audiolinux but more user-friendly to set up. Reasonable license cost. Runs both Roon core + HQPe (Linux version of HQP).
Cables: Ghent - Maybe unnecessary but picked up some Ghent ATX/CPU/DC cables.
Power: So far I've purchased most of the above except the power supply. At minimum I'll need a DC-ATX converter to use w/ an external LPS. HDPlex offers a relatively cheap converter which is popular, but Taiko just released one though much higher price. As for the LPS, Sean Jacobs or Paul Hynes seem to be the top choices but expensive. Cheaper alternatives would be a Keces P8 or HDPlex. Most seem to agree that the power supply makes the biggest SQ impact in a server so I'm patiently investigating options.
To summarize cost - about $1500 on the PC w/o power. +$600 for HQPe and Euphony license. +$200 on Ghent cabling. And finally +$1000 or so for mid-tier power, much more if stepping up to a Sean Jacobs DC3 or something. So all in all +/- $3300 for the custom server. Not cheap, but cheaper than popular options from Antipodes, Innuos, Aurender, etc. I'd reckon it'll sound as good if not better, for less $. Plus a custom build has the added advantage of total control and modularity to keep up w/ the ever changing digital audio scene.
