I know Mark Levinson supplies them with all their amps (in gold plate!) and you could make your own, as you suggest, out of a u-shaped piece of solid 10 (or was it 12?) AWG solid copper wire. Frankly I don't like the jumper idea anyway because they're hard on the female XLR, especially when taking them out. You want a better solution? Get a pair of Neutrik M XLR plugs and just short the appropriate pins inside, and plug 'em in!
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