Does using XLR cables (double voltage output) mean I can use lower powered amplifiers?

@thegreenman.
You can see my systems by clicking on my ID.

You have great speakers. It strikes me as you have great opportunities over time to improve your overall system to achieve greater SQ. I mean, I always look for the “best” component and then look at it’s potential if all components were upgraded to be of an equal and synergistic level. I don’t think you mentioned your sources. I’m assuming the Primaluna is an integrated amp.
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Of course the power is more than about just loudness, but given the sensitivity of your speakers the more powerful amp you are looking at is likely to sound much better.

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Given what you have said, have you looked at the Audio Research VT80se? You get warm tube… and really detailed. Now, this is my philosophy… but I try not to spread my money out and try always to step up… and never less than a 2x step up… since that creates some aspects of a sideways move. Anyway, if this strikes you as an interesting idea, go find a dealer and sit down and listen to one. If there isn’t one locally, take a little trip. I have actually flown across the country to audition stuff.

Well first of all Tube amps have much higher current than SS, so watts are not directly comparable. A 50 Watt Tube amp is really as powerful, if not more so than a 100 SS amp. The output of a balanced preamp is considerably louder than single ended, so in a way, perhaps you could get a way with a less powerful amp, but I don't think that's the best way to design a system, or should be prioritized. Best to buy components that have the sonic characteristics that you like and believe in, regardless of whether bal or se. Also its best to run thru and thru - balanced pre to balanced amp, se to se ...  The more important consideration when seeing if an amp is powerful enough is the efficiency of your speakers, and how hard or easy they are to drive.

@thegreenman    Amplifiers have both gain (usually fixed for a given amp) and a power output measured in watts.  It's important to understand the difference.  Check on-line for some articles.

What I'm interested in is a simply different but related question.  If you are using a high-gain preamp into a lower gain amp (e.g. the Benchmark on its medium or low settings), will the preamp impart more of its signature to the signal than with a more conventional set-up?  Or will that make no difference?

The amplifier gains the voltage difference between the xlr positive and negative signals, not the voltage magnitude. Since the gain is the same whether RCA or XLR, the power drawn by the speakers does not change, even though the balanced input is a higher voltage. An amplifier has two transistors on the input: one gets the positive XLR signal (or the RCA signal) and the second gets the negative XLR signal (nothing from an RCA input). The output signal is fed back at a fraction of its voltage to the second transistor and the difference between the two is amplified.