I think I fix everything, I guess it didn't play copy and paste from my impression in another forum, so I basically had to retype it
. If I miss something, I am not retyping it.
@draytonklammer I say go for it. It's $300 - $400 for resale typically, so it's not the most expensive to try out and it resell nicely the used market for some reason. I always see a Onkyo A800 gets grabbed within a day when it goes on sale, it's crazy. They should've just made more Onkyo A800 smh. As I said in my previous post, it's my favorite headphone for bass-heavy genres. Things like Classical music sometimes like Berlioz Symphonie Fantastique, especially movement 4, I say rap/hip hop is pretty good on it as well like the Pusha T new album It's Almost Dry, heavy synthesize bass pop like VALIS - 無窮プラトニック. Even rock music like Jimi Hendrix - Voodoo Child (slight return), and jrock like Band-Maid - From Now On is really good thanks to Gibson collab in tuning the headphone. Depending on your audio chain, the bass can be overpowering.
My favorite review for the Onkyo A800 is the below if you need more "influence". If you are disappointed by it for some reason either through comfort or you don't like the bass, you can always resale it so it's not the end of the world.

@draytonklammer I say go for it. It's $300 - $400 for resale typically, so it's not the most expensive to try out and it resell nicely the used market for some reason. I always see a Onkyo A800 gets grabbed within a day when it goes on sale, it's crazy. They should've just made more Onkyo A800 smh. As I said in my previous post, it's my favorite headphone for bass-heavy genres. Things like Classical music sometimes like Berlioz Symphonie Fantastique, especially movement 4, I say rap/hip hop is pretty good on it as well like the Pusha T new album It's Almost Dry, heavy synthesize bass pop like VALIS - 無窮プラトニック. Even rock music like Jimi Hendrix - Voodoo Child (slight return), and jrock like Band-Maid - From Now On is really good thanks to Gibson collab in tuning the headphone. Depending on your audio chain, the bass can be overpowering.
My favorite review for the Onkyo A800 is the below if you need more "influence". If you are disappointed by it for some reason either through comfort or you don't like the bass, you can always resale it so it's not the end of the world.
@protoss, its awesome such a modestly priced headphone is your favorite, which is high praise given your extensive experience. It reminds me of a headfier who owned a he90, r10, qualia, utopia, 009, etc..., and their favorite was a grado ps1000. Just shows that personal preference is king.
I hear your point of having a reference for good sound, especially as a check and balance to the soaring prices of modern flagships, which is getting ridiculous and pricing out folks like myself from this hobby. However, I'm not sure if the Harmon curve is it. IMO, evaluating based on a frequency curve is quite reductionistic, and does not take into account the multitude of factors that constitute good sound.
Regarding the A800's, I appreciate Protoss for the pro tip on grabbing a pair. I find them to be a very competent headphone that punches way above its price tag. Mine was purchased used with a generic aftermarket cable, so I may not be hearing their full glory, but here are some brief impressions:
Overall, the A800's may be my new reference for acoustic instruments. Listening to Yiruma playing piano as I write this, and the sound pulls at my heart strings. However, there are several headphones I would choose over the A800's for vocals, even perhaps the humble HD650's. It is my understanding that Onkyo collaborated with Gibson instruments for the tuning for the A800, and this collab really shows in how great acoustic instruments sound.
- The build quality is solid and I really like the ear pad mechanism that pivots and gives a great seal. Oversized headband is really comfy.
- They scale with better gear. On lesser gear, they sounded muddy, veiled, and boring. However, they sound vibrant, emotive, and grand when paired with my Abbas 2.2SE DAC and Woo WA5 Amp. I assume Protoss listens to his pair on his EC Studio B, so A800's may have good synergy with 300B tube amps.
- Bass digs deep and bass notes have a nice heft/weight/rumble with good definition. Not as tight or punchy as my ZMF's, but feels just as powerful and more controlled, and perhaps more accurate. The A800 sounds like the Z1R bass done right. There is an ever-present sub-bass on familiar tracks that I am not used to.
- Treble is clear and crisp, and has nice sparkle to it. Not rolled off and not harsh on good recordings. However, on non-acoustic recordings (e.g., popular music), treble can be metallic and screechy, and vocals sibilant and strident.
- Wish for a bit more midrange clarity. Neither veiled or recessed, but lacking some of the nuances that flesh out the intonations and emotions in vocals. Perhaps some bass bleeding into mid-range, which gives a weight and a richness to vocals, but at expense of expressive/nimble-ness. Male voices sound better than female.
- Details/resolution/transparency approaches summit-fi, but fall short of most electrostatics and some high-end planars. However, the detail presentation sounds more realistic than a headphone like a Raal that pushes details forward and can be fatiguing.
- Overall flow of the music is natural, but seems a bit slow after listening to faster headphones. The music never gets ahead of itself, unlike the Raal and Jade 2's which make music sound like its playing on 1.5x speed. However, the music does not flow like water compared to my Jade 2's, or does not have the toe tapping effect like my Aeolus.
- Size of sound stage morphs (intimate to large) based on recording. Images seem locked into place. Really good depth, sounds 3-D with tubes. Realistic instrument separation. Maintains good control and separation during fast and complex passages.
- On good recordings, there are no weird peaks or dips. Everything sounds like the real thing. However, they scale down with poor or synthetic recordings.
- Acoustic instruments sound really (really) good. Natural timbre. Piano, percussions, wind and string instruments all sound natural and real, and have a depth and weight to them. Sounds just pop followed by a natural decay. You can hear the inner detail of each instrument. Really brings out the emotion in instruments. Best I've heard LA4's Best Friend album.
- The A800's pair well with a musical and energetic DAC/AMP's and can sound boring off the wrong gear. This is unlike the TH900 which sound fun on most pairings.