Just got back to giving HQPlayer another try (current version 4.13.1). For the first time I can see running it continuously as a default for my Roon headphone sessions. My primary DAC is a Metrum Adagio (still on DAC2, waiting for DAC3 upgrade in the mail) via I2s at 192khz (shaper Gauss1, limit 20bit). Right now listening to my current SR1 chain Adagio->Ayon Spheris III->HSA-1a. Very nice and fatigue free sound for many different genres (unlike past HQPlayer experiments).
3 takeaways to share –
Several of the new filters bring distinctly new possibilities over previous versions, including sinc-L, sinc-MX, and ext3. One that I had overlooked and has now become my favorite: poly-sinc-gauss-xl.
Feasibility of HQP has increased significantly for me since I moved to a Mac Mini M1 (16GB RAM) on my desk, which is completely silent and sufficiently powerful to run HQP in the background (unlike Intel/AMD machines where that would have sent the fans spinning or otherwise impeded smooth system usage). Mac Mini M1 base configuration can be had for less than $600k and the form factor is brilliant (not many smaller systems around). Upcoming rumored M1X or M2 revision should stretch to higher bit rate DSD resampling as well (not sure if that wouldn’t still be asking too much from the current gen - fortunately I don’t need DSD).
Read the Friendly Manual - specifically pages 16-19 (filter choices). I recently started to experiment with apodizing (apod) vs non-apod filters, this list will help you find equivalent options and more systematically determine what works best for you in your system. For the longest time I was simply overwhelmed by the many choices, investing 10 minutes to understand the documentation was foundational to being able to getting value from HQP (instead of trying recommendations from other people, which was my previous approach that got me nowhere).