Three and four string courses are less common than they used to be, but that was the common stringing arrangement for hundreds of years. Two string course dulcimers have only become the norm within the past 40 or 50 and that's a drop in the bucket for a 2000 year old instrument. There is certainly some volume difference, but better string materials, better research on tonewoods, better design and construction techniques, better rail caps, etc. have negated most of the volume difference. My HD's have no problem carrying outdoor venues and large halls either. Nor would HD's from Hudson, Dusty Strings, Chris Foss, and others.

Don's problem lies with the band he's in which amplifies other instruments as well and no HD can compete with that. Also multiple string courses will potentially increase the sympathetic harmonics even more and make any electric amplifying harder yet.

But it does sound like your friend has a really neat dulcimer...and I bet tension IS a problem!!!

catspaw