Oomph or pressure?

Yes he does, for amps with low input impedance (<20khoms) that aren’t passive friendly, you need a unity gain buffer (no gain as he infers) and those amps thankfully are very not common place, and are around 5% of the market share. some Class-D and some First Watt, Pass Labs

Any amp that is 33kohm or "industry standard input of >47kohm" or higher is fine for any passive pre without the need for a unity gain buffer.

As for active preamps with gain they are not needed in this world any more, and are a left over from phono days when a preamp needed gain.

Even Pass Labs now has lowered the gain of many of their amps from the common 28-34db, down to the low 20’s, just so his and other high gain preamps can be used with most of the volume range they have, instead of being at 9 o’clock for loud!!

Since all digital sources make way too much voltage to clip any amp made

Not just digital even analogue sources, tuners, phono stages etc etc. Have more than enough voltage to clip just about any poweramp.

Cheers George

52tiger
Emia autoformer as my preamp. It sounds fantastic but one thing I noticed is I have to turn the volume up quite a bit to get any oomph out of it. thanks, Scott

Nothing wrong with having to do that, as Nelson Pass explains below.
Scott, passives rule!!, they are the most transparent/dynamic way of getting the source signal to the amp with control over the volume. Only better is direct source to amp (but you need a level control in the source) 

Nelson Pass,

"We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."

Cheers George