http://espsurgex.com/product/digital-qc/
I leave dac and amp on always as well. I use these to protect my audio and computer gear. They are primarily found protecting 15k/25k office machines.
The protection tech is different than common MOV protection. These things work, and are 20 amp rated.
A much cheaper alternative to this:
http://espsurgex.com/product/standalone/
Edit: One word of caution with these SPs, you must be 50' minimum from the main for these to work properly. But they don't sacrifice themselves usually and last forever unless directly hit, according to AMETEK. Some amazing testimonials out there on how good the protection is.