Too much power?

It really depends on one's speakers and system setup on how much power you need... With mine, they demand 0,01-0,01W with 0,2W peaks when I listen to them loud. So, my needs are below 1/5 of a watt... 1 watt for me is already splurging, and I rarely go there, only for concert-level experiences.

In general, as the amplifier gets more powerful, it can only be done through additional gain stages in the amplifier that erode the soundfloor. (Which is the low level details).

Most speakers are completely incapable of reproducing low soundfloors, so there's seemingly not much left missing as one climbs to even 5000WPC with the so pervasive "I need an arc-welder just to nudge"-type loudspeakers. Yet, provided sensitive speakers, going from 1W to 20W can already be a deal-breaker as already a noticeable layer of the soundfloor is lost, which might be subtle when you hear it first time in your life - yet, when you live with it, and are used to it, it will mean a LOT to loose it....

Just because you have the same manufacturer but two different models, does not mean that they will sound the same. The old Adcom smaller amps sounded better than the more powerful models.  You need to be happy with your choice and move on if that makes sense.

Happy Listening.

I have 450wpc but can still get great dynamics with less than 1 watt. Just depends on how well your components match..

I find the ideal volume depends on your whole system. But in general, the better my system has gotten, the less volume is needed. 
 

Over the decades I have pursued this hobby, more power has increased the punch and fullness in solid state amps. Although, for less power tube amps bested them overall.
 

Looking over your system, if I were you I would look to upgrade my preamp before looking to increase the power of your amps. I would guess that a really good audiophile preamp would increase details and midrange bloom and have a huge improvement on the overall performance of your system. I would recommend the best used Audio Research, VAC, Conrad Johnson or Presto preamp you can afford. Then you can revisit the amp issue later.

More power isn’t always the answer in hifi. My speakers are 92db sensitivity and I also listen mostly in the 65-80 db range.  Probably using 2-25 watts of power. 
Maybe I missed it, but what’s the rest of your system?