Each to their own. ASR I have stopped paying attention to long ago. If my ears are happy, I’m happy.
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I have access to professional grade measurement system at work but after some exchanges with the audio engineers, I’m quite certain that it’s not very useful for general consumers like myself. The only few times I check the measurement is when I want to make sure (to a certain extent) that the transducer I’m getting doesn’t have a rolled off lows because I tend to like my sub-bass intact, and when I, with my limited EQ knowledge try to mess with the FR. Unless you’re professionally working on this field or a reviewer who use this type of measurement equipment often, I just can’t find the value often revered by other general consumers in this hobby.
I started getting into audiophile stuff around 1998. At the time, it was understood that THX was merely a marketing gimmick to sell home theater equipment, and had nothing to do with making good music. If you go onto recording forums, you’ll see all of the audio engineers drooling over tube mics and transformer-based microphone preamps that they can saturate instead of clip. On the recording end of things, everybody wants vintage sound - rich harmonics and subtle tape compression. On the audiophile side of things, you have a few different camps - solid state vs. tube, in the audience vs. on the stage presentation, etc. But the general ethos amongst audiophiles is to try to listen to the recording as faithfully to the original intention of the artists, producers, engineers, etc. as possible. Some audiophiles interpret that to mean as little distortion as possible. Others interpret that to mean as musical-sounding as possible, regardless of the specs. I don’t know about you all, but I’ve had my most enjoyable listening experiences with Class-A power amps, whether tube or solid state, and they all distort like crazy. In the end, if you’re just thinking about your music, you’re not enjoying it. If you get lost in the moment with your favorite album, if you’re suddenly transported to the recording studio or the performance venue, that’s what matters, not the specs.
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Frequency response is only one part of how we perceive the sonic characteristics of amplifiers. Things like damping factor, slew rate, amount of negative feedback and where it’s applied, amplifier class, crossover distortion, transformer coupled vs. capacitor coupled, odd vs. even harmonic distortion, and more, all have an audible effect.
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Have you heard the THX amps? how do they compare to other amps in their class?
I have listened to other THX-certified amps, but haven’t gotten my hands on a 789 yet. In general, my impression of THX-certified amps is that they’re great for movie sound effects, and terrible for music.
“Class” here has to do with amplifier topology. It doesn’t have to do with any sort of rating in terms of price or sound quality. A class-A amplifier has its output devices (tubes or transistors) all amplify the entire waveform. That’s often referred to as single-ended. I’ve never seen a Class-A THX-certified amp. Their distortion specs are too high, even though they sound amazing. Other classes are generally either push-pull amps, or digital switching amps. In push-pull, one set of output devices amplifies the positive side of the waveform, while another set of output devices amplifies the negative part of the waveform. Where the waveform transitions between negative and positive, the circuit creates something called crossover distortion. The big advantage of push-pull circuits is that you can turn off your output devices when they aren’t in use. Those fractions of a second that they’re off, result in tons of power saved, tons of heat not generated, and the ability to generate much more power into the output signal. Your typical class-A amp won’t deliver more than 10 watts per channel (30 WPC is the max I’ve personally encountered), but it’s not uncommon to see a class-AB amp rated at 50 WPC RMS or more. Switching amps (class-D, class-T) in effect generate an output signal by switching the output devices on and off several thousand times per second, essentially recreating the waveform from data, rather than amplifying an electrical input. These amps are very power efficient, but the sound quality tends to lag behind other amplifier topologies.
To get THX certification, you need very low distortion specs. But you can artificially lower your THD by adding global negative feedback, which tends to make music measure better and sound worse.
In general, there are two categories of approaches: mid-fi, and audiophile. The mid-fi approach is to try to make all the specs look as good as possible on paper, using whatever circuit design trickery is needed. The audiophile approach says that the perceptual sound quality is the most important thing, and that generally results in very simple circuits with very high quality parts. THX tends to care more about specs than about subjective sound quality, and so audiophiles tend to view it as marketing and not an indicator of sound quality.
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Any recommendations in the 300$-500$ THX price range?
Rule No1: Never trust the first guy on the job!
Reviewers in the hobby who meassure mostly get their measurement wrong (and if not their measurements, they make it worthless by not compensating for the setup).
This is the frequency response from a 150mm long copper rod (longitudinal), yes I took these myself:
You get that by hitting the rod ONCE not by hammering it with a frequency sweep.
For the less initiated: Spike (or Needle) pulses contain all frequencies. In this case from 5 to 150kHz (there is a limitation in the measurement rig used for this here).
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In general I agree with what you’re saying about distortion and THX’s goals. I just want to be clear about one thing. My understanding is that THX certification for home theater products was about the amp, preamp, receiver, or speakers reaching certain measurement standards for SPL, distortion, and frequency response. They didn’t necessarily care what amp topology or driver type etc. the manufacturer used to get there. There was also THX post-processing for Dolby Digital and DTS codecs that rolled off the highs because some film sound was aggressively bright. So in essence, the THX certificate in those days was more or less a stamp of approval. THX headphone amplifier technology is a specific type of amplifier topology that uses op-amps and some form of feed-forward or feedback design (there’s been discussion on elsewhere on this forum which one THX is) to get those ultra low distortion numbers. To summarize, THX home theater certification was a stamp of approval that measurement standards were met regardless of how a manufacturer got there; THX headphone amp tech is a type of amplifier topology - unless I completely missed somethingand all this is bovine feces (apologies if that’s the case). However, this distinction still aligns with your main point that the THX ethos has been more about achieving measurements than how it actually sounds.
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Correct, it’s mainly theater stuff
Pretty much yeah, that’s mainly why so many companies all try to recreate the sound of classic preamps or consoles or tape etc
I would say that depends on the engineer as not everyone is going for a vintage sound, really depends on the type of music for that one
In the good way I would hope 
I would say this really depends, I have heard some shit thx cert amps and some excellent thx cert amps, it really just depends on the actual manufacture, I could care less about the actual certification and moreso about the amp at hand
So, I would say in the high end I have heard excellent class d, excellent class a, excellent class a/b, I really wouldn’t group performance by topology, it’s really hard to make a blanket statement like that
Unfortunate but true lol
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Apparently there’s way too many ways to hate music or hardware on this thread…Confused I am.
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I think hate is too strong of a word to describe it. In general, very few of us has a complete picture of how things going to sound since we don’t have the ability to audition 99.9% of popular sound equipment available out there. All we can do is to characterize certain things based on what others said about them and try to paint a picture in our head on how things would sound in a setup we’re trying to put together. Personally I don’t pay much attention to a characterization made by others without a full context. We have to remember that even when something presented to us with full context, it’s still heavily based on someone’s opinion due to the subjective nature of this hobby.
In my opinion, if you apply the above mindset to everything you read on audio forum, you’ll be more at ease when trying to navigate through them. There’s no certainty on things like this until your own ear and brain decide if you enjoy the sound or not.
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Absolutely, and even then lol
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It’s a disease really 
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I’m not going to say disease, moreso a crippling addiction lol
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It’s an addiction all right but let’s try our best to not make it a crippling one 
My bad, was speaking for myself there
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With that statement I expect an updated diagram of your setup to drool over.
The THX AAA implementation in the headphone amps out there, Monoprice 887, etc…really dont have anything to do with movies…
Its all about a Class AB headphone amp with very, very low nose and distortion measurements…
They have met the design goals exceedingly well.
Whether the end result pleases you is a different story…
I had the Monoprice 887 version for a few months and I sold it.
Alex
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I could care less about a diagram. I want a picture!