What is a cost effective way to level match, for comparing different hifi components?


Over the next little while I am planning on trying out some new DACs in my stereo system, and I know that it is important to make sure that sound levels are carefully matched when comparing. So I would like to ask others here how they do this? I realize that these days we all have smartphones and can download apps to measure SPLs. Is this accurate enough for careful comparisons. I wouldn’t mind getting some ideas from others on how they do this, and what might be the best way.
troidelover1499
The only reason I can think of to do something like this is to learn to judge volume. Listen to some music, take your reading, play the next thing at a volume you think is the same, take another reading. When the readings match pretty close you have a good sense of volume. From that point on toss the stupid meter it will only distract you from what really matters which is learning to listen. 
Use a voltmeter you can't level match with a SPL meter. You also need to do the test blind other than that just pick whichever one you think sounds better and don't worry about.
You also need to do the test blind
Do you REALLY need to be blind to judge equipment? I don't see very well. Is THAT good enough? Or do I need to go blind completely in order to assess the sound characteristics? If so, I think I'd opt for just  keeping my old Dac and my vision....or what's left of it. Wow! I never knew it was so demanding to buy audio equipment.