Keep in mind that I don't drink the piss.
From Wikipedia "Blended Scotch whisky constitutes over 90% of the whisky produced in Scotland.[citation needed] Blended Scotch whiskies contain both malt whisky and grain whisky. They were initially created as an alternative to single malt whiskies which were considered by some to be too harsh. Master blenders combine the various malts and grain whiskies to produce a consistent "brand style". Notable blended Scotch whisky brands include Dewar's, Johnnie Walker, Cutty Sark, J&B, The Famous Grouse, and Chivas Regal."
Also from Wikipedia "A blended whisky (or whiskey) is the product of blending different types of whiskies. It is generally the product of mixing one or more single malt whiskies (made from 100 percent malted grain such as barley or rye) together with other grain whiskies or neutral grain spirits. Scotland, Ireland, and Canada are the most common countries of origin for blends. A mix of single malts only, without grain whisky, is called a vatted malt.
Most blended whiskies do not list an age. When a blended whisky does so, each individual malt and grain whisky must be at least as old as the age listed. Two of the most widely known examples of blended whisky are Johnnie Walker and Seagram's Seven Crown, but there are many others such as Jameson, Pigs Nose, Old St Andrews and Isle of Skye.
Grain whisky and other 'fillers' are usually much cheaper to produce than single malts, so blends containing them are usually much cheaper to buy. Most cocktails and mixed drinks that call for whisky use blended whisky. This is primarily for cost reasons, and secondarily because the complex flavours of single malt whiskies would be overshadowed by the mixer(s). Scotch purists generally consider blended whisky to be an inferior drink to the single malt Scotch varieties. Others might argue that blending allows for the creation of smoother or more desirable flavors, and many experts agree that top-quality blends can rival certain single-malts in overall flavor and drinking enjoyment."
Neither of them make any mention of bringing together single malts from different distilleries.
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— Samuel Johnson
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2010 & 2012 CTN NASCAR Fantasy League Champion. No lemurs were harmed in the winning of these titles.
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, but most blends are actually predominately grain whisky (corn [maize] or rye) with some malt whisky from several distilleries. Note that Johnnie Walker (the world's most popular Scotch whisky) is a blend of over 35 whiskies - and you will not find a Johnnie Walker single malt. 
