Audio Horizons TP 2.0 Preamplifier

I use the original, White Teflon Halo 7's.

There's a brief description of the sonic character for each ring type (white, nickel, black)

Gammajo,
I use mytle wood blocks under the Audio Horizons DAC and preamp. It is decidedly better than a softer isolation material. The myrtle wood benefit is a lower noise floor.

Cedar, using the myrtle wood directly under the unit, do you then also have something to kill vibrations into the shelf from the ground, protecting the unit from outside vibration?

My impression (no science here) is that the myrtle wood is particularly good at draining vibration off and away from the audio gear. My audio shelves are suspended from the wall. I can jump next to them and not disturb a turntable playing. For this reason, I perceive the value of the myrtle wood blocks as "vibration drained away" rather than as "vibration prevented from reaching." It might work both ways - I can't tell.
Perhaps I should add that my shelves are wood, too - plywood with many coats of paint applied.

in the event one would like to upgrade the stock tubes without purchasing them from the manufacturer (as in I already have a new unit delivered on Friday) what tubes and from where should I be looking?