Everyone is slightly different....

personally, I found my Smartwool headband to be too narrow and thin to really keep my ears warm well. What I discovered however is that an Ibex neck gaiter will do it ALL!:

The Ibex neck gaiters are double layer merino- very warm and plenty wide. I go out walking for miles in 20 degree cold and wear a neck gaiter over my shak neck but tucked under any jacket or vest. I can also pull it up to cover my chin if it gets cold. Sometimes if my ears are getting cold I just pull the gaiter up and fold an edge under a bit and it makes a fabulous thick warm headband that really covers your whole ear area and even most of your head too if you don't fold it much. If it starts to drizzle I just wear it like a hat with a hole on top, it looks like a cute chimney hat like that. Then if I get overheated, I just take the neck gaiter off and it folds right into my pocket, so it's more convenient than carrying a bulky hat around if you are trekking along and having to keep carrying all your stuff. On really cold days sometimes I will go for my 5 mile walk wearing TWO neck gaiters- one on my neck and one as a wide headband ear cover. I know I will warm up during my walk and then I can either fold one or two up and pocket them, or sometimes I have even twisted the gaiters into figure-8's and just stuck them on my wrists while I finish my walk.