How do I check for impedance between components?Manuals often publish the impedance specifications in the back of the book.
Dkzzzz (Threads | Answers)
Otherwise, you can ask the manufacturer, or you can sometimes find the info in reviews, especially the measurements section of Stereophile reviews.
It may be difficult to obtain the input impedance spec of the Music Hall Maven. I have read more than one post where Roy Hall basically told the person asking the question that the specs weren't available.