What actually determines volume power? Is it watts?

So what spec do I look at instead of wattage?

Depends on your speakers.

What are you playing?

The issue may be the speaker / amp matching and knowing your speakers would help.  Your speakers may be out of dynamic range or they may have a difficult impedance profile. 

Assuming you had easy to drive speakers, and they were not even a little stressed, then Wattage would help you understand how much more you needed.  Doubling of power = 3 dB SPL.  Doubling perceived volume = 10x the power, and 10 dB louder.

OP:

Lets simplify.  If you feel you are "almost there" with your current amp and you are looking for a reason to upgrade, go ahead.  However if you feel there's a big gap between how loud you can play and how loud you want to play the math isn't in favor of a 2x power difference being your solution.

It's also possible your amp has plenty of juice but it's your speakers which are compressing and reaching their thermal and/or mechanical limits.  They do have limits. 

So, if you feel you have a big gap between where you are and where you want to go, it's more likely to be solved by higher efficiency speakers.

Have fun shopping!

Erik

Hello dman777.  By now, you have waded through a lot of anwers to your question. They are all pretty good. Let's talk first about speaker sensitivity. A speaker rated at 84 db (we assume the ratings are honest) will play 6 db softer than a speaker rated at 90 db. It will take four times the power to drive the 84 db rated speaker to the same volume (loudness?) in the same room. A 94 db rated speaker would need only one tenth the power to play the same loudness as the 84 db rated speaker.

The advertisements don't tell you that, but it's true. Do you have some input device with meters on it to indicate the strength of the output signal. Watch the needles dance. A 10 db increase calls for ten times the power from an amp. A 20 db increase call for 100 (Yikes!) times the power from the amp. Amps that double their output power into four ohms verses what they put out at eight ohms have pretty hefty power supplies. A two ohm rating at four times the power output indicates a really strong power supply. Check the ratings of tube amps verses solid state amps. Also look at the distortion percentages at rated power. Tube amps are often rated with maximim power at 10% (harmonic) distortion. Solid state amps are often rated a so much power at 1% distortion. Tube amps can seldom double their output power into a 4 ohm load verses an 8 ohm load. All of this means that when the drum goes BOOM! an amp is called upon to put out a lot of juice in a hurry! Can the amp do it? You want an amp that never has to sweat. An amp rated at 100 watts that has to put our 150 on occasion (not even a 3db difference in apparent loudness) will sound less pleasant than the same input with the same speakers in the same room, with a 200 watt rated amp and not have a problem at all. The more efficient your speakers are, the happier your amp will be. I hope this helped. Enjoy the music!

@baconboy 

Bryston offers many different colors/finishes on their faceplates, although they are the same design.

Regards,

barts

@dman777 you’ve sparked one of the best threads I’ve seen in a long time with many members taking deep dives into watts / amperage / speaker relationship.  A lot of members took a lot of time to delve into the topic and provided a lot of great advice and guidance.  I’d echo what others already have form a speaker / amp pairing.  Gaining Volume from an Amp relative to your speakers is more complex than just looking at the speaker sensitivity rating and the watts rating on the amp.  Improving performance / volume with your current speakers is more complex than manufacture #’s on an amp and or speakers. As many have referenced, having visibility to your set up would really open up the type of detailed advice that could be provided, not just your speakers but everything in the chain.  Gain values apply to DAC’s, Streamers, CD players, Turntables and that impacts the volume knob on your Yamaha Reciever.  
 

Best analogy I’ve seen when talking about amplifier performance and the ability for an amp to drive a set of speakers is that to an engine, not all Horsepower is created equal, following that logic, not all Watts are created equal.  For an engine, torque plays a huge role in performance of the HP that an engine produces, where and when the torque and HP shows up in the RPM range of the engine plays a huge role in how the performance of the engine translates to the performance of the car.  It’s the same for an amplifier, not all watts are created equally.  In SS amps, so much of the control of the speaker has to do with the amps ability to control the woofer, drivers and as many others have referenced, deal with the wide variation of impedance requirements.  A large power supply coupled with the proper design / implementation is what allows the combination of amperage and watts that drive speakers to effortless volume.  Having a reserve of power to then drive watts / amperage is what gives an amp headroom.  When you pair an amp with speakers you need to understand what type of car you are dropping the engine into.  You wouldn’t drop a race car engine in a Ford Super Duty 350 and you wouldn’t drop a diesel 6.7 liter V8 into a Toyota Camry.  Same principles apply when pairing an amp with speakers.  You need the right combo of watts / amperage, one without the other however won’t get you to fully realize a speakers full potential.  An amp with a lower wattage rating but a higher amperage rating, power supply that can deliver more current will almost always drive speakers to higher levels than an amp that has a higher watts rating but lacks the power supply to deliver amperage / current.  Again though, grab a pair of high efficiency speakers and hook them up to high amp / watt Coda or Krell amps and you won’t get past turning your equipment on and you could have music playing rather loudly with the volume dial at zero, create as many problems as not having enough watts / power.  
 

Thanks for starting the thread, it generated a ton of thoughtful, insightful replies within the Gon community, good luck.