IIIrd Tyme Out has won the bluegrass association's vocal group of the year award many years running ( Quicksilver won it back this past year). They lead vocal is formerly the lead vocal for the old Doyle Lawson and Quicksilver, so if you have Quicksilver recordings from the 80's it sounds strikingly similar to IIIrd tyme out.

Isaacs are as WYSIWYG describes.