ABSOLUTELY! The lack of switchable pre/headphone outs by means of a physical switch is the single reason I myself have not purchased a Jotunheim a long time ago. I use headphone amp/dac/pre combo devices for my work as well as occasional listening for pleasure, and switch between headphones and monitors many (sometimes numerous) times a day. Not having a switch to chose one or the other is unfortunately a deal-breaker.
I did order a Jot 2 now that it has at least the pre-out switch (should be here today, yay) but it is still not an ideal scenario, because personally I never want both phones and monitors putting out signal at the same time, whether when I work or listen to music. When would this be desirable to anyone, actually? Separate rooms perhaps -- in which case it's not really the product anyway -- I can't think of anything else?
BTW,
@Jason Stoddard , is this by any chance something that can be addressed via a firmware update -- turn off the headphones when pre outs are on? Or is it all hardwired?
Having the physical switch do either preamp outs OR headphones would open up these products immediately to a large pro market as well (not the intended audience of the product perhaps but extra sales couldn't hurt?) I can see plenty of people replacing their Grace Designs and what not in an instant. I know of entire pro facilities adopting a consumer-grade device simply because there was nothing comparable in the pro arena with a certain feature and in a given price range. In one case it was influenced by yours truly and involved a headphone amp/dac combo in fact -- a Nuforce unit at the time -- simply because it had an AES input along with all other desireable features, was 6 times cheaper than the closest pro-audio alternative, and sounded better, too...
I'm just sayin'
My copy is pretty much untrackable in that area now even with an arm/cartridge combo that could easily handle it. Something about a hard, pointy object falling down the side of a cliff and then bouncing when it hits the bottom. 
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