I dunno.
What is dark matter?
If you take an iron magnet, and heat it up, it stops being a magnet, right? (Right.) If the core of the earth is molten iron, why does the earth have magnetic fields?
If an audiophile falls in the forest, does it still sound better on vinyl?
Some things just are.
If an audiophile falls in the forest sounds better in plaster.
We still have 2 great questions unanswered 
Good advice already offered. A Topping DAC amp combo is likely holding your 6XX back. I have the same headphones and noticed improvements in going to separate components and producers that lean more toward engaging sound signatures as opposed to Topping which leans more toward analytical.
Sometimes quality is more important than quantity. You are likely aware, but some transducers require higher current and not just more power. 100 watts from Class A, Class AB, and Class D amplifiers sound different, as does single ended versus push pull.
For your stated budget in order to unleash the 6XX, I’d suggest something like a Schiit Modi 3+ or Modius, Jot 2 or Vali 2+, and Loki tone control.
I haven’t followed the whole thread, but we seek to mind our tone here.
@rho I have no problem with your tone. I fully understand (and I mean I fully understand) your skepticism and your position, since it is identical to mine as of about 2 years ago. 
@bpcarb points out that this forum is unlike all others on the net because we really try to be very careful with our speech. I have thick skin. In fact my wife often thinks my skull is nothing but skin and bone, but I know there are eardrums hidden in there somewhere,
Let me call out some of the folks who have more than just reference-quality eardrums in their noggins, and see if we can get a good answer for this phenomenon. Because this is actually not in question. I suggest you grab your 6xx and plug it in to somebody’s more powerful amp. If your Topping DAC has a line out, use that to power the amp so you know you are not listening to a DAC change and not simply more power.
@generic, @antdroid, @Resolve, @Nimweth and others, please help offer an explanation that we can point to in the future, as this comes up at least once a month somewhere on the forum.
Added later: You too @Tchoupitoulas giver of hearts, and speaking of hearts, @ValentineLuke and @prfallon69
And you @FLTWS, you’re going to be stuck in snow just like I will be, so take a DIY break, and help answer.
Anyone with cats in their icon is OK in my book.
hello,
what about cable?
zmf upgrade?
danacabel_
norne?
another brand?
thanks for respond…
I am on my phone at the moment, which makes things difficult, but try doing a search for voltage swing.
Internet communication can be tricky since we don’t have voice, facial and body language cues.
I think what’s happening is that the term “power” is being used as the single descriptive of what is needed to scale the sound of the HD600-series.
rho is saying that power is power so that can’t be the totality of the situation.
I’m not an amp designer but from what I read important aspects are the power supply and amount of energy held in reserve and available to respond to short term spikes of output demand.
These demands appear when you compare the power required at average listening level to power needed for the spikes. The peak power required can be a factor of ten over the average power requirement.
Large power supplies and large capacitors are used to provide the power reserve. Doing a good job of this requires additional and expensive parts. This adds up to a more expensive amp.
Much of the market is focused on specs so it becomes a harder sell when the $2,500 amp supplies a max of 200mw. So that leads to amps with adequate reserves having a higher power rating even when it’s not needed for most headphone usage.
So then “HD600 scales with higher power” can make sense since all the better sounding amps have more power, but it’s not actually the power doing the scaling.
I’m happy to be corrected on all this.
Hello
I’m afraid I am not the best person to ask about this as I have little knowledge of electrical theory or technical data.
Who is your post directed at? I literally had that page open when I typed my previous post.
Post removed. It was not directed at you, and my tone was awful. I apologize for hastily phoning in a reply to a complex topic.
If I have more time later today, I will work on an actual reply.
I’ll let Torq join in but he’s probably very busy at the moment.
But extra headroom for when power spikes are needed or to compensate for low end bass needs. Extra headroom to combat distortion that typically happens at the high end of amp’s rated power. Extra power to kill your electricity bill.
Some amps limit the amount of voltage as well, and some headphones are current-driven, so you may not get the full amount of current or voltage for the most ideal situation.
I am not an EE nor an amp designer, nor do I know what I am talking about. This is just stuff I hear.’
Power is a contributing factor. Given my experience with multiple amps that have a wide range of power delivery capabilities (anywhere between a few hundred milliwatts of headroom, to others that have one or several orders of magnitude more milliwatts of headroom) I can confidently say that in general, more is better. HOWEVER… As you noted later in your post, there are many more factors to it than that.
More powerful amplifiers are almost always more expensive than less expensive amplifiers. More powerful amplifiers may then require more expensive production methods, better components, more complex designs, or many other factors leading to both increased price and power ratings. So, which is responsible for the better sound? The power increase? The different components? The different / more complex design?
If you really want to dig deeper into that, you have to start asking questions like: Are the given power specs peak or RMS? Is there feedback in the circuit? Are the individual components used fast/powerful/quiet/accurate/efficient/etc enough to affect the sound? Are there so many components in the signal path that they cumulatively change the sonics? Are there capacitors in the signal path? Is the power clean? How does the performance of the circuit change under different loads?
Does it matter?
Does knowing all of these things change the sound of the amp? No. If the amp sounds good to you, then it sounds good to you. Seeing as this is the end goal, does all of that truly matter? Even knowing all the specs doesn’t necessarily help you make an informed buying decision. There are TONS of incredibly well built, well spec’d, well designed products that sound like absolute flaming canine poopoo.
So, to answer your question of “Why would 100mW from a 250mW amp sound different from 100mW from a 2.5W amp” would be: You can’t answer this just by providing power numbers. You have to dig deeper. Sometimes digging that deep just isn’t worth it. Knowing all the specifications still won’t tell you how something sounds.
So, what should you do if you can’t rely on specs? The alternative is rely on other people’s opinions and impressions on products. This is just as big of a mine field than everything I’ve covered above. Hype, placebo, confirmation bias, financial motivations, ignorance/inexperience, dunning kruger effect, herd mentality, peer pressure, and many other issues make this unattractive as a source of valid data.
The only cure for all of this is to go out and experience how things sound for yourself. Reinforce that by finding a few reviewers who’s preferences and opinions closely match your own. When I say there are 4 people in this world who’s ears I trust, I’m not exaggerating. For everyone else, I have to compensate their opinions with a hefty amount of skepticism.
This is both the most helpful and useless advice anyone can give someone new to the hobby. It’s useless because it doesn’t help you make an informed decision on what to buy next, and it’s the most helpful because it is, at it’s core, the most truthful aspect about gear anyone can give you.
Now, to address the underlying concern prompting your question, I can confirm that the HD600/650 does absolutely scale with better gear, and I wouldn’t ever use the products you have now with them. That’s just my experience with those headphones.
Good luck.
Dust is settling in regards to my run down the rabbit hold. I’m writing in this thread as opinions are still appreciated.
I’ve got the Schiit Jotunheim and Bitfrost2 for dac and amp, I think these will be what I stick with for now.
I’ve got the Sundara and Arya. Every time I put the Sundara on, I keep reaching for the Arya. I’ll end up selling the Sundara, I don’t keep extra equipment around, I keep moving up or sometimes sideways. I’m going to give Focal a chance, see how the fit and sound compares to the Arya. I keep hearing about the Elex but it’s a one time deal, not like I can try it and send it back if it doesn’t work. So, If I feel the Focal is a better fit, I much pick up the Elex and make that my stopping point. Still some choosing on the headphone front.
I am considering IEM’s for work when I’m sitting at the desk. Prefer something that works off the iphone and no additional devices to drag around. I’ve considered the Blessing 2 or the S8, linsoul t3 all the way up to the HiFiFo Kinera Nanna. Lots of choices still on that front.
In your prior post, you said “all other things remaining equal”. This is the kicker. All other things aren’t remaining equal.
For example: in a class AB amplifier capable of a max of 250mW, the bias of Class A power vs class AB power may be set anywhere in that range. In that same design, but capable of 10x the total output, the bias may also be set anywhere in the range. In this one example of how the power can be different, we now see that we have four possible outcomes at 100mW:
Amp 1 running in class A, and Amp 2 running in class AB;
Amp 1 running in class AB, and Amp 2 running in class AB;
AMp 1 running in class AB, and Amp 2 running in class A;
Amp 1 running in class A, Amp 2 running in class A.
This is one way that the first 100 mW can be different.
Yes, but you write very good reviews, and have golden ears.
It really depends on your preferences for sound signature. The IEM you mentioned are all good each one with highs and lows. Among all the ones you mentioned I’d go with the Blessing 2 but as I wrote it is subjective.
About Focals I can tell you only positive things. Given the headphones you’re using I’m sure the Elex won’t disappoint you. For a fair comparison with Arya anyway I’d go with the Clears. But it’s just for a fair comparison about the position Clears and Aryas have in the marketing target.
I hope this can help.
Enjoy
I have the Clears coming in tomorrow, so I’ll be able to compare the two (Arya and Clear). Comfort is just as import as sound to me. I have the Blessing 2 coming Tuesday, so I’ll be able to give them a try. Thanks for the input.
Not sure I’m the best at describing, I’ve always listened and never really thought about the music I’m listening to. Never had really good listening devices. I don’t like things to bright, what I’d call treble. I like a mid and semi bass but I think natural the way things were recorded, I’d prefer to hear that way, I’d prefer not for the bass to overtake the music I’m listening to. Just my initial thoughts so far.
So this is by no means the educated explanation of amps/wattage and the like. Just my 2 cents regarding my experience with the 6xx and the question posed in the original post. So, the 6xx is the first real quality headphone I got. Everything prior being something cheap from Circuit City, Best Buy, etc. I would say the 6xx is a bit of a catch 22 in that it is bargain entry into the “audiophile” but can also drag you much further in. As once you have it you hear about this “scaling”. I got it a little over a year ago (Oct ‘19 to be exact) and only ran it out of my Denon AVR for about 6 months. Thought it sounded great. I then bought my first dac (su-8) and amp (THX 887) and was impressed by the improvement. I now have an even better amp and tubes and can again attest to the “scaling” as being real. So now to my point…your original question was in regard to what to upgrade first iems or headphones. I certainly wouldn’t recommend throwing big $$$ at improving a $200 headphone. I mean it all depends on what direction you want and how far you want to go…I now have 3 amps and 8 headphones. The 6xx could be endgame and you could slightly upgrade gear or you could get better cans that could work fine with your current amp/dac. Going with iems certainly requires less gear so the overhead is much less. That’s where I think I’d go. Actually, I did… I have like 8 iems now too. This hobby’s the 
Enjoy the ride ! Tons of great experience/knowledge here
You’re welcome. As i start I believe you have very good ideas about sound quality and great equipment to start the journey.
I’m sure you won’t be disappointed.
I wait for your impressions.
Enjoy.
One other thing to consider with certain headphones is their impedance curves and how they’ll react to specific headphone amplifiers and their output impedance. Some of those Sennheiser and Focal open-back dynamic drivers will see a small mid-bass bump with higher impedance headphone amplifiers, and this is not a power thing.
Damping factor can also come into play, though I admit I dont totally understand this as much. @driftingbunnies and I were discussing this last night actually over on discord. But it seems to us that higher impedance headphones like Sennheisers and ZMF headphones sound better when they arent overly damped by a ultra-low impedance headphone amplifier and sound better with something 20+ ohms OI.
This does go a bit against the whole LOWER IMPEDANCE is better, but it doesn’t necessarily go against the rule of 8 either.
Impedance matters A LOT with in-ears. many will not run well on higher impedanec amps.