What actually determines volume power? Is it watts?

Another approach, assuming you don’t know anyone that would loan you an amp to try out is to buy an amp from a company that allows a trial period and a no fault return policy if it doesn’t meet the need. VTV produces a range of class D amps that have a trial period as part of the terms of sale and it might be worth exploring that avenue. If you have an aversion to class D as some people do, this would not be a choice you would make, but I would encourage you to consider class D as a possible solution. Currently produced modules from Hypex and Purifi have excellent sonic characteristics along with the advantages of light weight, high power, especially for low impedance loads. Plus they are extremely efficient so power consumption is considerably less than any other possible choice. That might not mean much to you if you are running a 2 channel only system. But electric power costs are going up and quite substantially in my area. I think class D is the future of high end audio, especially for home theater, because of all the advantages it brings to the table.

For the money u spent on this amp, there are plenty of better options out there. Like the one mentioned , Hegel, Belles, Bryston, audio research all have plenty of current to drive speakers to sound full, at a lower volume. But all these people are right. Are you looking for music at levels that make your ears bleed? Most people in a standard room depending on speaker efficiency, couldn’t go past 20-30 watts. I mean one time with a pair of 4 ohm speakers with an efficiency of 90db I hit a peak of 60 watts and the spl was 110 db. Your talking hearing loss down the road. Just my 2 cents.

I run older Harmon Kardon Citation 22 amplifiers. These are pretty loud, even through my 91db JBL L100t3's. But, I always wanted a little more than the amp could provide. So, I bought another one. Switches on the back enable me to use them as mono blocks. The two amps provide 800 watts total power which makes the music much louder than even I can stand and I'm not beating the hell outta them.

@dman

If, as some suggest, you look at changing both your speakers and your integrated amplifier, could I suggest you look at powered speakers where the manufacturer has effectively done the matching for you?

The little KEF LS50s are the knockout class-leader in their price range and play much, much louder than their appearance suggests. Each active speaker includes a 260-Watt class D amplifier for the bass and a 100-Watt class A/B amplifier for the treble.  So you effectively get bi-amplification and monobloc operation.  A bonus is that these units have concentric bass and treble drivers, so they throw a coherent wavefront resulting in a massive soundstage and a much bigger than usual listening area.

There are much more expensive powered speakers in the KEF range worth considering as well.

As others have said, one important role of the power amplifier is to control the momentum of a dynamic speaker, so it actually stops moving in short timeframes.  Eliminating speaker wires allows the amplifier feedback circuit to directly interact with the speaker

dman77

For every 3 db SPL increase in output volume requires a doubling of the amplifier watts being used. So if your speaker sensitivity is 88 db, which means that it takes 1 watt of amplifier power to drive that speaker output to 88 db at 1K Hz measured 3 feet away. It will take 2 watts to drive it to 91 db, 4 watts to get to 94 db, 128 watts to get to 109 db and 256 watts to get to 111 db and that is before we consider the effects of the inverse square law which states that you will loose 6 db of SPL for every doubling of distance from the source.

To answer your question more directly, it’s a combination of amplifier power, speaker sensitivity, source level, room size, music type (low frequencies will eat more power than high) and I’m sure there are other factors I don’t know about. A 200 watt amp is a 200 watt amp and will drive a speaker close to the same volume regardless of price, but a better amp may do it a little cleaner, with better low end or  better peak output, etc. etc.