I just put my FM3T up against my Ampero Stage II and I’m enlightened.

Just did a quick sound check on the OG Amp Academy, Atomic Amplifier-Firebox MKII, Blackstar Dual Drive and all sounded significantly better. The Iridium sounded just a bit better.

I’ll need to adjust IR’s and “amp” settings/patches some but the underlying foundation of tone is considerably more solid.

I JUST UPGRADED ALL OF MY GEAR! Woo-Hoo!!! I’m not making any recommendations on specific headphones but I did my research and think I did well. The important lesson here though is getting the right headphones that match your headphone amp is key regardless of which sound signature/design/brand/price point will suit you and your preferences. The guys above me are absolutely right.

But another shoutout to @OrganicZed for being a helpful hero today. Thank You Man!

I’m very glad to have been of service. IMO, this is an aspect of digital modeling / headphone use that doesn’t get enough attention.

I first encountered the issue when I plugged my brand new set of high end custom molded IEMs into the Axe-FX III and they sounded worse than the $30 universals I had been using. It wasn’t in the realm of subjectively worse, it was comically worse. I was expecting to be blown away by the sound improvement but was instead blown away with disappointment.

Fortunately, I’m the type of dork who reads technical specs, user manuals, and forum posts. I was able to piece together that the impedance was mismatched and that might be causing the poor performance. I bought a super low output impedance headphone amp with the hope that it would solve the problem. The difference was very substantial and now I run all of my headphones off of that amp.

Ideally you want your headphones to have around 8x the output impedance of the amplifier (or more). The amp that Fractal chose for this generation of hardware is great for driving high impedance headphones (280 Ohms or more), but is a poor choice for even moderately low impedance headphones. I really hope they pick a better spec amp for the next generation of hardware.
 
Headphones change their frequency response over time. My DT 990 Pro did have exaggerated highs when they were brand new. Three years later, it's a whole different story.
I've had my DT 990 Pro 250 Ohms for 14 years. They still have massively overhyped highs. It's so easy to hear if you remove the correction, or just compare them to something that is more even out of the box.

Reviews state this, you can see this if you look at e.g AutoEQ curves.
 
I was able to piece together that the impedance was mismatched and that might be causing the poor performance. I bought a super low output impedance headphone amp with the hope that it would solve the problem. The difference was very substantial and now I run all of my headphones off of that amp.

Ideally you want your headphones to have around 8x the output impedance of the amplifier (or more). The amp that Fractal chose for this generation of hardware is great for driving high impedance headphones (280 Ohms or more), but is a poor choice for even moderately low impedance headphones. I really hope they pick a better spec amp for the next generation of hardware.

Before this gets picked up by the AI bots, let me add that I don’t think this is correct.

The headphone amps in the FM3 and Axe-Fx 3 handle low impedance drivers just as well as high impedance ones.
I’ve been using 40 Ohm Meze Audio headphones, connected directly to the device, for years. Plus Sony MDR, Beyer 880/990 Pro, Bose and others.

Impedance is not a measurement of quality. The old 1/8th rule is an audiophile thing that gets blown out of proportion often.

Some relevant quotes:


 
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I don't put much stock in headphones. If you want a true assessment, disable cab modeling and plug into a good guitar cab in a good room (cabs are not near-field like monitors so the room matters). That way you can take out the IR piece and focus on the amp modeling and how good it is.

But in case that's not his usual monitoring scenario, it's not worth comparing that way.
 
because otherwise he’s just using the turd modeling in Logic.

Fwiw, the really driven amps are as shitty as it gets (which actually is making me wonder as most of Logic's other internal plugin offerings are pretty good, sometimes even excellent), but there's some good tones to be found in the clean and EOB realm (not necessarily authentic, though).
 
Before this gets picked up by the AI bots, let me add that I don’t think this is correct.

The headphone amps in the FM3 and Axe-Fx 3 handle low impedance drivers just as well as high impedance ones.
I’ve been using 40 Ohm Meze Audio headphones, connected directly to the device, for years. Plus Sony MDR, Beyer 880/990 Pro, Bose and others.

Impedance is not a measurement of quality. The old 1/8th rule is an audiophile thing that gets blown out of proportion often.

Some relevant quotes:



The output impedance of an amplifier affects the damping factor. If the damping factor is low, the headphones will perform in a manner that is not optimal. Unless physics have changed or the Axe-FX is using some additional circuitry to compensate for this (Cliff is a wizard, so I am open to that possibility), then the relatively high output impedance of the headphone amplifier is a legitimate concern for the end user to be aware of.

You may be correct that the 1/8 rule used by audiophiles is too conservative. I have not done any of my own testing. I am repeating what I have read on the subject. I have also read that some people actually like the “warmth” that under damped systems lend to the low end response and they intentionally choose components that will exhibit this behavior.

In my specific case, the 6 Ohm IEMs were severely under damped and I was hearing uncontrolled low end. The drivers were making clicking sounds when low notes were palm muted even at low volume. It was objectively undesirable behavior. Routing the Axe-FX into an amplifier with an output impedance rated at less than 0.1 Ohm solved the issue. It was not a matter of the amplifier in the Axe-FX being under powered for my very sensitive (easy to drive) IEMs or an inherently bad sounding circuit, it simply could not prevent the drivers from moving in an uncontrolled manner with low frequency signals.
 
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I've had my DT 990 Pro 250 Ohms for 14 years. They still have massively overhyped highs. It's so easy to hear if you remove the correction, or just compare them to something that is more even out of the box.

Reviews state this, you can see this if you look at e.g AutoEQ curves.
I guess we'll have to agree to disagree.
 
The output impedance of an amplifier affects the damping factor. If the damping factor is low, the headphones will perform in a manner that is not optimal. Unless physics have changed or the Axe-FX is using some additional circuitry to compensate for this (Cliff is a wizard, so I am open to that possibility), then the relatively high output impedance of the headphone amplifier is a legitimate concern for the end user to be aware of.

You may be correct that the 1/8 rule used by audiophiles is too conservative. I have not done any of my own testing. I am repeating what I have read on the subject. I have also read that some people actually like the “warmth” that under damped systems lend to the low end response and they intentionally choose components that will exhibit this behavior.

In my specific case, the 6 Ohm IEMs were severely under damped and I was hearing uncontrolled low end. The drivers were making clicking sounds when low notes were palm muteded even at low volume. It was objectively undesirable behavior. Routing the Axe-FX into an amplifier with an output impedance rated at less than 0.1 Ohm solved the issue. It was not a matter of the amplifier in the Axe-FX being under powered for my very sensitive (easy to drive) IEMs or an inherently bad sounding circuit, it simply could not prevent the drivers from moving in an uncontrolled manner with low frequency signals.
I’m not enough of a headphone expert to know whether one of you is more right than the other. I suspect there is truth in both and I don’t think for one second that anyone is acting in less than 100% good faith. Well close anyway!

If I had to guess the primary root causes for my experience it would likely be two factors. One being that using 37 Ohm headphones with a 35 Ohm headphone amp is likely not ideal. I don’t know that for sure but it seems at least possible that operating so close to the minimum spec would result in some audible impact. And I was doing my version of critical listening. So I was paying very close attention and I did come to my conclusions while flying blindly. The Ohm issue wasn’t even on my radar.

Secondly, I suspect that the Beyerdynamic headphones are just better headphones. I bought the Yamaha’s not to get the best headphones possible but because I wanted “inexpensive” studio cans whose sound signature was one I was presumably familiar with and hopefully be consistent with the Yamaha studio monitors I use. Yamaha is a brand that I would trust to be fairly committed to having their studio labeled products consistent. Perhaps that’s not true or perhaps what works for monitors doesn’t work for headphones. I can’t say as I am not a studio engineer. I’m just a guitarist and self-proclaimed audiofile.

At the end of the day I learned some things and ended up with a greatly better situation due to the suggestions here. And perhaps, hopefully, someone can learn from my mistakes. And I also feel a bit better about my ability to trust what I hear as well as what I think about it… my ability to choose the tones that I consider good for me. I think that’s kinda cool too.

I’ve had an eye opening weekend thanks to @OrganicZed caring enough to try to help me with his own experiences. How freaking awesome is that? 👍🏻😎👍🏻
 
Just understand the Beyerdynamics likely require a lot of correction. You can use the global EQ and dig up AutoEQ curves for the headphones.

I recommend you run both modelers into an audio interface and check if that sounds better.
I do expect that headphones matter so what do you guys think is the best pair to use for modelers or is it dependent on the model or it seems?? I use the old standby Sony’s and it seem to work pretty well
 
I do expect that headphones matter so what do you guys think is the best pair to use for modelers or is it dependent on the model or it seems?? I use the old standby Sony’s and it seem to work pretty well
I like the Sennheiser HD650/6XX (6XX is the actual model). No correction needed, just needs a capable enough headphone amp on the modeler.
 
I have the Sennheiser HD600s and they were a huge upgrade from my previous Audio Technica M20x
 
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