Preamp Output Capacitor: Mundorf Supreme vs. Supreme Silver Oil

This thread is extremely educational but at the risk of sounding a bit nerdy, I just want to say that these sort of “tweaks” should be handled with extreme care and sometimes best left to qualified techs and/or experienced DIY folks. Almost all these gears, especially the tube gears, run on some real serious voltages and the slightest mistake can have irreversible health and even life ending results. Capacitors in particular need to be handled with care for obvious reasons - they can hold charge for a while. 
Sorry, just wanted to throw that out there as I hate to see/hear anyone get hurt.

“...came along with the ODAM suggestion. They’re smaller and cheaper than the Miflex so I’m looking forward to trying them...”

Where do you find the ODAM capacitors selling cheaper than the Miflex?
A 0.47uF Miflex is around $25 vs. a 0.47 Vcap ODAM priced at $84. The price differential is a little less for larger uF values but definitely not cheaper. 
I’m very tempted to try the ODAMs in my Aric Audio Unlimited preamp already upgraded with the  Audyn True Copper capacitors. A clear improvement over the stock red Audyns.  Anyone has experience with the newer Audyn True Copper Max? For a 2.2uF value they are about the same price as the ODAMs. 

t_ramey, thanks. I’m also looking at 2.2uF values for my preamp and I now see the prices are on par for 630 volts rated model when buying a pair and ODAM pair is cheaper for the ones rated at 400 volts.

Thanks for the input. One quick and hopefully non controversial question: do any of these capacitors need to be installed in a specific direction even though they are not marked for direction? I have seen some tube amplifier building/repair instructional videos where the designer/builder uses a special device to measure a certain parameter to determine the “correct“ direction for installing the capacitor, e.g., foil side towards the tube socket, etc., or something like that if I remember correctly. He claimed it makes difference. Just wondering.

Thanks for the link. I found the video where i saw the capacitor polarity topic discussed.

https://www.youtube.com/watch?v=BnR_DLd1PDI&feature=youtu.be

P.S. Sorry if a bit off topic but might be of interest.

Sorry if I’m asking the obvious but when changing brands do you always use the same exact uF value as replacement/upgrade? I suspect the answer is yes but I still wondered if the different material construction, design technology, etc., or even the desired sonic outcome, might positively impact the outcome if a slightly lower or higher values were substituted instead. 

Could someone explain why adding a 0.01uF capacitor in parallel/bypass with a 2.2uF capacitor improves sound quality? 
If this is way off topic and I’ll delete the post and ask elsewhere.
Thanks.

Thanks. I’m not questioning the results, one way or the other, just wondering why and how it makes a difference. Apparently, in the chip design the different value and material parallel/bypass capacitors are used to push the inductance of the capacitor to higher frequencies and the combined impedance(s) of the capacitors is lowered across a broader frequency range. But that’s at MHz region. I’m guessing the same/similar phenomenon occurs in audio. Otherwise, on the surface you’re just adding the capacitances of the two capacitors.

Thank you for taking the time to answer the question. I'm just glad to see some folks take the time and the expense to experiment and share their results. Given that the results are system/circuit dependent, I guess I'll need to perform my own experiment, albeit an expensive one, and see how it goes.   
P.S. If I ever decide to get an MHDT Orchid, I know who to contact for advice or how to make it sound better.