Any reason NOT to have multicore checked?

So it seems that I get a 10-20% speed increase in HQPlayer (tested using free running benchmark) when the “Multicore DSP” option is Checked, rather than greyed.

Given as this isn’t checked by default I wanted to ask, is there any reason NOT to have this checked? Would there be any potential loss in quality etc?

I know that for example running everything on CUDA could potentially bring floating point approximation into consideration but should enabling/forcing multicore have any problems?

No. Unless you have reason to be afraid of the security implications there is no reason to leave performance on the table.
See for example: https://www.techradar.com/news/intel-cpus-can-be-exploited-unless-you-disable-hyper-threading-linux-dev-claims

I’d say this is a no-brainer to keep on in a home environment.

If it works better with the option enabled, you can keep it enabled. The two options are there because it is not always straightforward to determine if it brings performance benefit or penalty…

There is no need to worry about CUDA, what I’ve tested it produces same results to the degree it applies to the cases where it is being normally used. IOW, I cannot show a HQPlayer case where it would do worse.

Ah fantastic thank you for the info!
On a slightly different note, i’m currently considering purchasing an HQPlayer Pro license, but from what I understand, it can’t actually output flac at 768khz? (I’m planning to use it to upsample my entire library so this would prevent that from working unless I then manually tagged every individual file)

Is there a way to, or will in future be a way to output 768khz to a file that retains metadata/tags (preferably flac)?