Passive preamp

+1 @ghdprentice 

There’s more to it than just active vs. passive. It boils down to an overall design, quality of parts, power supply. There’s no such thing as a wire with gain. Anything in the signal chain will impart its sonic signature. A good property designed active preamp with beefy power supply always wins in my experience. Solid state or tubed. In case of tubes you have the added 2nd and 3rd order harmonic distortion that makes tubes sound pleasing (softer and fuller and in high end preamps no sacrifice in resolution and holographic soundstage). Personal preference, synergy and your perception of ideal sound is what will make it or break it. If you like your Schiit in passive mode, just enjoy it!

op

this may help you learn about the topic 

My worry is that your system is good as your weakest link.  Which might be the schiit.  I'm using a Starkrimson Ultra class D amp (which I just added), and Dynaudio Heritage Specials as well as Innous Zen mk3 and Bricasti M3 DAC. I was hoping that a 'budget' preamp might work in passive mode.  But I'm having second thoughts now.

Passive preamps can sound amazing, but it takes much more care in component matching. You can in essence relying on the output of your source (in my case, my DAC) to drive the amp (in my case Coincident Frankstein 300b). If the input sensitivity of the amp is high enough and the output of your source is high enough, then a passive preamp can sound absolutely glorious (keep in mind that you need to select cables very carefully as well and avoid any longer lengths). Get it wrong and it's going to sound flat and uninspiring.

On the other hand, a really good active preamp will remove most, if not all, of these constrictions and can very well make your entire system sound better.