Less volume with a more powerful amp

I used to own a Onkyo receiver and have since bought a Marantz AV 7005 Pre-amp plus a Rotel RMB 1095. I used to listen to music at -15db but now have to turn it up to - 6 or 7 db to get the same volume . The new setup has 60 watts per channel more power.
Amp gain (sensitivity), not output power, determines the necessary level setting.
Is particular amp sensitivity a predetermined engineering goal for a given design or is it an incidental outcome?
I do not think there is a single answer. Since it is interdependent with other design parameters, it is not an independent variable.

Obviously, sensitivity needs to fall within a useful range for commercial success but some designers have specific targets and others do not.
I don't mean to pester you but is high sensitivity commensurate with a low noise floor given all other performance parameters are of a high standard?
High sensitivity is not commensurate wit ha low noise floor as a 'given'
Usually the sensitivity is based on the design of the manufactureres matching preamp.
Okay, thank you. I guess what I'm getting at is where the threshold of signal loss begins. Is it interdependent on the gain of the pre or will it occur at a certain point regardless? And will the noise floor begin to add to it? Or is it a separate issue?
The significance of the gain and of the SNR is dependent on what you feed it. I do not know what you mean by "the threshold of signal loss."
I'm assuming there's a point at which the lack of sensitivity begins to prevent part of the signal from being transferred or amplified.
Actually, a lower sensitivity (higher numerical value) is commensurate with a lower noise floor.
In theory but, in practice, it would depend on the output capabilities of the preamp.
Thank you all for putting things in perspective.