My methodology: informal.
I do not live in an "acoustically perfect" environment; I live in a house. I do not have a hobby of running scientifically proper blind tests of ... well, anything... I'm only going by what I perceived, with my gear, in my house, in my imperfect environment. I walk around. I live my life. I listen to music at various times throughout the day, a wide variety of music, from classical to country. Movies are a night-time thing. Occassionally, I have the luxury of kicking back in my recliner in the "sweetspot" and get to listen more "critically" if I choose.
Over several weeks. Swapping in and out. One right next to each other. With and without room correction software (for the Marantz. I didn't use any software with the Pioneer.) Same Heresy-4 speakers, same speaker cables, cd players, and everything else, with the Pioneer Elite and the Marantz sr7015. Going in, I actually wanted and expected that I'd like the Marantz sr7015 better, but I didn't. My expectations were overturned. So, I returned the brand-new Marantz. I'm sure some people would have come to a different conclusion. But, I preferred the sound I get from the Pioneer.
Why? I don't know and I don't care...! "Maybe the Pioneer is distorting in some way that you like..." Maybe so, I didn't break out the meters, you know? What I care about is to get the sound that I like best in the budget I have, given that the receiver has the practical necessities... although the Marantz was more up to date in that regard, w built in streaming and all that new processing potential, but that didn't change the fact that I preferred the Pioneer's sound.
That was as scientific as I needed or wanted to get. It was clear to me there was a different sonic character between the two amps; they did not sound the same, even when both were straight up stock w no correction applied, and both with music and with surround sound movie watching.
For the Marantz nr1200, it was over the course of several months: it compared with vintage gear. Same speakers: epi 100s and epi 50s. Pioneer sx-450, Harman Kardon 430, and Marantz 2238, all professionally refurbished. Swapping around, sometimes one right after another, head-to-head, sometimes leaving one in for days, and then putting in another one. I actually wanted the 2238 to win, as it is super-cool retro eye candy, and it sounds really nice. As I narrowed things down, however, the first to get sold was the sx-450, then the Marantz 2238, then the HK 430, leaving me with what, to me, in my room, with my speakers, was the winner: nr1200.
Those are my experiences and conclusions based on my non-laboratory, real-world informal listening tests over the course of weeks and months. If anybody thinks I wasn't actually hearing any "real" differences and it was all in my head, well... OK. We can dig into the weeds of individual abilities and differences and preferences and the whole question of what's real and what's not, perception vs. reality, but I'm not teaching nor taking a philosophy class at the moment. Think on the absurdity, though, of the following statement: "You didn't hear what you heard." I am reporting my perceptual experiences with various amps in my little world, and my conclusions were surprising even to myself.
And, it's like this pertinent quote from C-Net, in the article
Do All Amplifiers Sound Exactly The Same?:
"The
$25 Lepai LP2020+ integrated stereo amplifier
plays exactly the same notes as a $42,000
D'Agostino Momentum amplifier. Exactly. The rhythms, melodies, and harmonies are all the same. Granted, the Momentum is considerably more powerful, so it can play louder, the bass will be more potent, the treble is clearer, and the stereo sound stage takes on an almost three-dimensional quality, but the notes, they're no different.
For me, the real difference between the two amps is how they translate music into sound. The emotional connection to the music is stronger through the D'Agostino Momentum; it's a giant step closer to hearing all of the energy/passion the musicians were putting into the music when they recorded it.
The "notes" may be the same, but flavors are a very different story. With amps, the sound, as opposed to notes, is the first thing to go. A great amp strips away the artifice of sound reproduction and lets more of the music shine through.
Vacuum tube amplifiers measure and sound different, some say better, some say worse than solid-state amps, but again they both play the same notes.
There are those folks who believe the only scientific way to settle this debate is to "blind test" listeners to "see" if they can hear the difference. That's cool, if that's what you want to do. Prove that all amps sound the same, and then buy the Lepai LP2020A+ and live happily ever after. Me, I'll stick with my
Pass Labs XA100.5 amps, and live happily ever after."