Quote Originally Posted by Barry View Post
Speakers using more than one drive unit were regarded as 'professional' and were, I believe, not subject to purchase tax.
Indeed but there was also a driver size limit with too small = domestic. They could quote the longer dimension of the elliptical cone and get round it that way!

This is according to the book "Leak: Firsts in high fidelity" re the Leak Mini-Sandwich.