As you know, of all the liquid libations out there sake has by far the greatest temperature swing points from volcanic lava hot to slushy frozen cold. Each zone is well defined and well "preached" by the brewers. Every sake has a defined temperature point that it is best served. Some labels will actually include temperature points as a guide.
In a word, you can heat any sake! But typically the higher-end Daiginjos and sakes like Nigori (unfiltered) just don't perform well with higher temperatures. The whole point is to get the sake to open up and to fire on all levels in the palate. Sometimes when you drink a clean and pristine Ginjo right out of the fridge it is too clean (some people like that) and you don't get its full flavor or feeling playing field. When you warm a sake it's like opening it up! Too much heat and you get a different beast all together, but a gently warmed sake is like looking over the edge of a vista, you see a new side to the sake.
So specifically to answer your question I prefer warming sakes to super heating them. The question then becomes when should I not warm my sake? Ha! When there is a heat wave outside.
In this light warming sake is sort of a game unto itself. If you gently warm a sake and then pour the contents into relatively cool ceramic cups then it cools too quickly and you get a tepid temperature. I actually heat my cups up rather than make the sake hotter, because I think too much heat changes the sake.
Warming sake is fun, and of course it's more fun with people. So they next time you have people over I recommend trying the same sake at several temperature points. Taste it right out of the fridge! Pre-pour some so you can try at room temp. Next throw some real heat at it. Then lastly try it gently warmed around 105 degrees and see which zone you prefer. Finally remember the word nuru-kan, because this will then become your favorite temperature zone and you can order sakes that way!
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