Sorry I step away to mess with my speakers for a minute
When using music I get to 0+dB at that point the speakers can still go but the receiver doesn't have enough gas in the tank so I have to back it down to -10dB to be safe, speakers are 3ft off the front wall and a foot off the sidewall length of the room is 2.5x the size of the width.
So now we are getting to the root cause of your problem. Up straight it inappropriate use and abuse of equipment.
Using a system turned up loud to provide whole house audio is not a viable solution.
You need speakers in those spaces or separate audio systems if you want sound in more than one room. Here is why.
At zero db any input at the specified input voltage will produce the maximum power available from that amp into the load. There will be no headroom.
Digital inputs are all pretty standard. So playing a CD at zero db will clip any device.
You need a minimum of 10 db headroom and really more for classical music.
To do what you are trying to do would require amps 10 times more powerful than what you have now, and expensive high powered speakers to match.
Putting that much power into speakers designed for domestic use will destroy them. The voice coils will frequently exceed their thermal limits as well as suffer severe thermal compression. The mechanical limits of the drivers will also be exceeded.
My rig is loud at -18 db. Occasionally I may push it to -12 db but not for long.
Given the dynamic range of the music I listen to, even at those settings requires 2 kW of audio power and half of the 14 amps are directly connected to the drivers so I'm not wasting half the power of those amps in a passive crossover.
Bottom line: - if you want to listen in other rooms of your house, then your upgrade is audio engineering specifically for those rooms, not more power in your existing room.
If you don't heed my advice you will destroy a lot of good equipment.
