Capacitors for HP filters in tube amps recommendations?

Well, everyone's "first hand experience" will be different. Wima makes excellent industrial caps. I used them in my Spectral DMC 10 rebuild as the final output coupling caps and they sounded good. But the Mundorf silver gold oils sounded much better in the DMC 10 by comparison. If there really was no difference (or the WIMA was superior) I doubt if Mundorf would continue to get the prices they charge over the Wima. As Nelson Pass states, audiophiles vote with their wallet.

I can't see ANY poly propylene cap out performing a teflon cap like the VH. This is quite commonly accepted and reinforced in reviews like the Humble Homemade  Cap tests. What a manufacturer uses in his product may be the result of a number of factors, sound quality being only one. Costs, size and availability may be others. For example, Bryston uses an electrolytic cap in the output of their BDA products, much to my chagrin. Speaking with their engineers, they "reassured" me that this cap was chosen from listening tests. My own tests with that cap removed proved they were sadly mistaken. The BDA sounded much better with that cap removed. BTW, Bryston only uses this cap to remove the very small DC offset, no other reason.

The Dahlquist DQ-LP1 crossover used a passive HP section.      It’s manual contains a chart (and formula) that you may find of interest.     https://sites.google.com/site/mpbarney/home/dahlquist-dq-lp1                When I was using my modded version, Michael Percy was my go-to guy, for Polypropylenes, Polystyrenes, etc, that he’d match to 1%, plus: a wide variety of other nice, parts/pieces/materials.      His service and expertise were consistently excellent.      Can’t swear that he’s still in business, since it’s been years, but- his site’s still up: https://www.percyaudio.com/Catalog.pdf         Personally; I never paralleled capacitors, unless they were identical, to avoid any possible time-constant disparities.

Personally; I never paralleled capacitors, unless they were identical, to avoid any possible time-constant disparities.

That's not a concern... capacitors in parallel will just sum in value (like resistors in series)... the source and load won't see any difference. In fact there are good reasons to parallel capacitors. It's easier to match the values for left and right channels (more combinations) plus statistically you'll get a tighter tolerance than specification (although you'll need to parallel quite a few to make much difference). You can achieve higher capacitance than is commonly available for a particular dielectric (I have used 5 x 10uF wima for DC blocking). Also multiple smaller packages will have a larger surface area than a single large package so heat dissipation is better.
If you want to go down the route of matching your own for around $25 you can get a cap meter that will measure 1pF to 20,000uF although you might want to factor in a few precision caps to use for calibration.

I said, "personally".        You’re welcome to your opinion, if you have one regarding time-constants (which is to what I referred, but- you never addressed) and anyone else’s, that you value.

I’ve read concerns from a couple of amplifier designers about time constant ramifications resulting from the use of bypass caps. They state that contrary to the opinion of some audiophiles, bypass caps are to be avoided whenever possible. The obvious question is: "What designer(s)?" I don’t at the moment recall, but it was a couple of biggies, on the level of Nelson Pass, if not in fact he himself.