How important is the pre-amp?

WOW mikelavigne ! You’re in rarified air, or rather the stratosphere. Good on ya. I love the listening room you built.

https://darko.audio/2015/11/the-select-dac-ii-msb-technologys-90000-da-converter/

I used to run a well-regarded passive line state (whose name escapes me) with my McCormack DNA-1, with CD source only, and loved it. McC made their own passive line stage that is still coveted when upgraded by Steve McCormack.

My sources are all digital, and I have thought of either getting one of the Tortuga passive stages (straight wire, no gain) into a DAC and then my amp, or something like the Chord Hugo TT2 DAC using that as the preamp too. And then I think that maybe a tube preamp would be fun, as I’ve never had tubes. But my whole system costs less than an exotic set of speaker cables!

Good thread, but the frustrating part is not being able to mix and match the various options in auditioning pieces (within budget), and trying to dial in the synergy. I have a short list of amps and preamps I like, but I have no idea which ones would play well together if of different brands. Therefore, I wonder if going to an integrated (Pass 60, Levinson, Aesthetix Mimas, Simaudio 600i V2) would alleviate that frustration, and then the DAC becomes the main variable. Hmmm.

How little I know, and wish I knew! re:

The issue with transformers is loading and inter-winding capacitance. All transformers have inter-winding capacitance. If the transformer is not loaded correctly (usually too lightly) the capacitance may play a role causing the frequency response to be less than flat. This coloration can be easily heard.

Transformers are called that because they transform impedance. It goes both ways; you're not insulated on the input from the output. So if the output load is reduced, so is the impedance on the input side.

What happens when you have a transformer with multiple taps used as a volume control? Since you are working with a variable turns ratio, to keep the transformer linear you need to have the correct load at both the input and output. You can't, as a designer, expect to always see the same source impedance and you certainly don't see the same load impedance since all power amps are different in that regard. On top of that you have the moving target of variable turns ratio.

So you'll need a lot of switch contacts, not just the ones to change taps but another set with resistor to correct for the changing load impedance as the turns ratio is varied.

This has to be done right, else the unit can introduce coloration.

It's all alchemy to me, what the great designers do. I'm glad for it though.