Well dogs, an alarm system, and.... guns. Also nice surveillance systems are cheap these days.
Audiophiles need to realize that they would be a target if low-lifes new what they had. Keeping a low profile is always good. Some people are really into their car and what not though so it could make it hard. I am not into cars so much and live in very moderate house and yes I do have all of the things I listed above...
Really I can not believe it when I hear stories about multiple break-ins at the same house. Many states are covered under the Castle Doctrine these days. Among defending family and your life in your home, it allows for some defense of property too. Some legal food for thought below. But to answer the posters question I would buy used Magnepan 1.6s. They look like junk but sound great.
"Physical Force in Defense of Property
A person is justified in using reasonable physical force when and to the extent he reasonably believes it necessary to (1) prevent attempted larceny or criminal mischief involving property or (2) regain property that he reasonably believes was stolen shortly before.
When defending property, deadly force may be used only when it is necessary to defend a person from the use or imminent use of deadly physical force or infliction or imminent infliction of great bodily harm as described above (CGS ยง 53a-21)."
Castle Doctorine