Are your amp comparison’s level adjusted?

I've used the Audio Tools meter on my iPhone to test things…works great.

Absolutely and positively 100% the only correct way to compare anything in my system.

Kenny.

I personally wouldn't find this device worth the cost. It seems better to  compare components over a span of time. Quick comparisons reveal differences, but don't tell the whole story. YMMV.

Listening levels being relatively matched is very important for the mentioned reasons. What the origins of the method and reasoning are, is a long drawn out explanation.

eg, when testing cables the listening levels should never allowed to change. Switch to different input or mute whens swapping cables...but never change levels.

Other methods like long term are part of the equation (and fundamental-critical!), but direct comparisons - level match. Then try both again at another listening level. And so on.