Gotta agree with Cap on this. We all know what our business equipment is capable of. We can't know what a house system is capable of nor if it's capable at all.
If you patch into a house system and it breaks, the onus is gonna be on you. You may wager that the old "We've been using this system for seventeen years without fail and you come in and break it" line is gonna be used to ream you a new one.
Never mind that the house "system" consists of dust-clogged Pyramid amps and cabinets. All you've gotta do is fry just one of those old peizo horn drivers... and the house owner may well try to get a new EV rig out of it. Any business can be sued.
Remember the old adage: You break it, you buy it.
If you patch into a house system and it breaks, the onus is gonna be on you. You may wager that the old "We've been using this system for seventeen years without fail and you come in and break it" line is gonna be used to ream you a new one.
Never mind that the house "system" consists of dust-clogged Pyramid amps and cabinets. All you've gotta do is fry just one of those old peizo horn drivers... and the house owner may well try to get a new EV rig out of it. Any business can be sued.
Remember the old adage: You break it, you buy it.
That's why one is a vet in the biz...not a casualty because of it!! 
