Founded in 1947 by Carl Thom in Hazel Park. His first store was also a Hallmark Cards outlet which sold albums as well. Thom sold the business to his son Bill in 1991. By 1998 the chain had 38 stores and was a major Ticketmaster outlet. By the early 2000's 17 stores were closed. Competition from Best Buy and Wal-Mart was cited as the reason. Digital, downloadable music also played a role. The Royal Oak and Berkley stores survived until 2003 and 2004 respectively, specializing in classical music. The Berkley store was converted to an f.y.e. store but retained the Harmony House decor until 2019. [Wikipedia]
On a personal note, I LIVED at the Dearborn store when it was going in the 80's and early 90's. It had a significant classical section as well. There was nothing like endlessly going through the bins, trying to find some rare gem of an album. Harmony House was the Southeastern Michigan version of Sam Goody or Tower Records.