Entropy.

(Mostly just adding ont your statement, message is adressed to OP) 
Well, at least if youre looking to compare "clean" and relatively uncolored amps to smartphone outputs, such as the schiit magni or topping l30, for example. There's other options out there that will have pretty large differences, as they colour the sound in various ways. Subjective thoughts or preferences are not really predictable, you may perceive some differences in between say, your smartphone output or something like an apple 3.5mm dongle and another amplifier. 
 
Getting back on trackt, though, if you're content with what you have, and you don't see any issues, it's perfectly fine if you don't want to upgrade. If it ain't broke, don't fix it. 

The headphone output impedance is rated 470Ω (it's not a real headphone output), which would probably produce an extra dB or two of midbass bloat on the DT990 depending on the specific model, and the output power is severely limited into low impedance loads, so it won't drive certain headphones properly.
 
It's lower quality than the average modern motherboard in many respects, but if you can't hear the noise floor, aren't having issues with the lack of power, and prefer a bit of midbass boost, then there's no urgent reason to switch. Whether there will be a noticeable difference in sound quality is really up to what you consider noticeable. Compare the AX-570 headphone output to a smartphone output and see if the difference in sound is appreciable. The difference between a modern headphone amplifier and a smartphone jack are likely to be significantly smaller than the differences between the differences between the AX-570's headphone output and the smartphone jack, at least quality-wise (not power-wise).
 
 

Thread cleaned.
 
A reminder for everyone to please be civil and respectful to one another when discussing a difference of opinion.

Passive isolation is high at high frequencies and low at low frequencies. The 280Pro has minimal isolation below 200Hz. ANC attenuates low frequencies. Passive isolation is better than active isolation when possible, but in this case the only passive isolation on par with ANC headsets is going to be either high clamp force safety muffs or deep insertion IEMs.
 
32dB NRR is not the same thing as 32dB broadband attenuation; neither is NRR a good metric for noise isolation as opposed to hearing protection (and arguably, it's a bad metric for hearing protection too). The manufacturer gets to determine the test fit, allowing them to inflate clamp-force related effects; the computation is designed to favor higher frequency (rather than more audible) attenuation; and the NRR algorithm lets you bake in A-weighting, leading to significant overstatement of low frequency attenuation; technically open air has a 16dB NRR at 125Hz.
 
Having worn both the 280Pro and Sony/Bose ANC headphones, the 280 provides nowhere near the same amount of attenuation. None of them hold a candle to proper open-backs sound quality wise, but that's not a relevant comparison; for this particular use case, ANC is the way to go.

If the speaker has good directivity and the sidewall is in a small room odds are it won't smear and instead blend well creating a single psychoacoustic event.  This also gives the "appearance" of a larger soundstage outside of where the speakers are.  The bigger issue is if they're asymmetrical walls which may cause issues.  If on the other hand directivity is bad then absorbing isn't a bad idea . . .
 
Vertical reflections tend to impact timbre in comparison.
 
 
As for the decay discussion:
 
It's a medium to small room, waterfalls/CSD for the room really aren't important compared to say an auditorium.  In this case the value of CSD is tracking down timbre changing resonances which typically can be done with FR/Impedance plotting but CSD is another way of seeing it which may be easier for some.  The Q of the resonance is also important as some have effectively no audible impact whereas some others are.  CSD can help visualize it.

Actually I don't think I caught that bit. If that's the case, go hog wild.  But I will also echo what Derkoli said earlier: You should expect to trade out gear, and experiment a bit a bit until you land on something that works for you. 

One positive is that the first reflection point being your desk isn't as bad as your first reflection point a surface such as a side wall. The reflected signal will arrive not too long after the actual desired signal, which will reduce the effects of dynamic smearing.
 
I'd just spend the dosh now. No point spending 2.5k on a system, then upgrading everything to a 10k setup, if you can just do the 10k setup initially. I've gone through a tonne of gear, and not all of it was exactly amazing. Prime example being my Sonus Faber Aida's. Just go with something you're gonna enjoy. You can always sell it on at a minimal loss to try different gear.
 
In my bedroom, one wall has a set of shelves (12 of them, roughly 15cm between them, roughly 5M wide) with random stuff on it, and its genuinely an amazing diffusor. After hunting vibrations and adding diffusers to the other side wall, my bedroom is my second favourite listening room.
 
Of which speakers are basically the most important component of.
 
The rate of which a speaker "dies down" is a very real thing. It's measured by both designers and reviewers (Stereophile measures CSD often) and many factors can alter it. The biggest culprit usually is cabinet resonances.
 
A room just tends to exacerbate this issue.
 
In fact, Q Acoustics has an extremely specific technology to help combat CSD. The cabinet is built in 2 or 3 layers, with gel in between to convert the cabinet vibrations, which stem from the cabinet not being perfectly inert (resonating), into heat.

Well, here's an analogy
 
Someone is giving away an old car for free, but it doesn't drive at all
 
While someone else is selling an car with a decent driving experience and good gas economy
 
Sure, they are both cars, but in this case paying for the car is better than taking the free one

The only concern I would have is desk bounce.  You can get or make some very small stands to help get them off the surface by 6" - 12" or so.  The Salk likely won't have issues with the tweeter having limited dispersion, and the Genelec I linked may not be too bad either because of amazing directivity control in general.
 
I don't think desk reflections/bounce is a good reason to not invest in good speakers.  Studios have the same issues with consoles to a degree and still focus on buying quality equipment even with these issues in mind.

The answer to the first half is generally "it depends". Desk reflections (and resonances) very likely will be a noticeable issue, but there are things you can do about this. Keep in mind that lots and lots of control rooms (at least in the old days) had the nearfields placed on the meter bridge of a console, with a back wall some distance away (probably more than 3 feet, but not necessarily), and usually -you guessed it- a glass window looking out into the live room.
 
Mounting the speakers off the surface of the desk (as if they were on a meter bridge) solves a significant part of that problem. You may also want to look carefully into the desk itself to make sure it's not going to resonate.
 
The decision for how much to spend is up to you. There are advantages to buying more expensive equipment in this application, but most of the really expensive speakers are also quite big. Keep in mind that it's not uncommon for studios (well, those with the budget) to have $5000+ in nearfields, and their situation isn't all that different from yours. I have the 1992 equivalent of the Quested V2108 in a desk environment, and (with some careful considerations to avoid major acoustic issues) I get a pretty flat in-room response, and the resonances I hear aren't too severe.
 
Another useful point (that I think some people in this thread missed) is that objects in the room have an impact on acoustics, both positive and negative. My lab, for example, has a large back wall full of storage shelves with parts and equipment on them, mostly in wooden boxes. In practice, this is a surprisingly effective diffusor. Some "untreated" rooms actually have tolerable characteristics (it's luck, but it does happen) for this reason. 
 
The decision is up to you, and you'll know fairly quickly whether these potential issues need to be addressed. If you were trying to build a control room, the acoustic treatment issue might be a bit different, but what's good in a control room isn't necessarily what's fun to listen to. Part of this hobby is experimenting and learning new things.

I mean that a lot of producers use that exact model of Yamaha studio monitors, and a relatively inexpensive calibrated mic will get the response done pretty accurately. i.e. the same way a music producers setup is done.
 
There's a lot that goes into proper room treatment other than just buying panels and placing them around. For $10k I recommend you find out if there's actual experts to get the job done, and it won't be cheap. They have to measure the room and surface types, speaker placements, and reflection locations, then if they're any good, make custom panels. The material isn't cheap, and neither is the labor. If you're not willing to do that, tossing curtains over the windows and some random foam panels isn't enough for that kind of system. Also, just typically speaking, the more expensive speakers are for load sensitivity and pressure level output. Which in a room that small is unnecessary, unless you want to blow out your ears. And for that matter, actual heavy blackout theater style curtains are ~$100. And Walmart stuff won't cut it.
Spare room/den, whatever. Doesn't really matter. $10k on a stereo setup is ludicrous when proper room treatment and a $2500 setup will get you the same result as the mixing engineer. The thing about a properly balanced mixing system is if you input a 1k sine wave, the speaker should produce a 1k sine wave. This holds true for every speaker. THD and all that is effectively complete nonsense as long as it's below like .1%, which even dogshit speakers are. The primary point is, if you buy any decent set of speakers, it should be calibrated, and then it will sound pretty much the same as any other set. The timbre might vary slightly, but I'm honestly doubtful. If you calibrate your speakers in a treated room, you can get them to sound like pretty much any other speaker with a parametric EQ. Which, considering your playing from your PC, is freely available in EqualizerAPO.
 
Those Japanese dudes are spending fortunes on their kit and gear in rooms that clearly aren't designed for it. It's literally wasting money. That's also assuming all the snake oil they're buying is actually true. Which it isn't.
 
No, every calibrated test I've seen of SVS subs had a very flat response across the frequency range from like 20hz to 200hz or something. They're ridiculous. Why you think that makes them bad for music is beyond me. There's no logic behind that. The most important thing for a sub is placement. You're not getting a big sub, or even a small sub, that's hitting 20hz without causing shit to rattle. Again, 50hz is 50hz. If it's too loud, turn it down. The SVS subs should even have the phase on a pot, so placement can be even looser.
 
 
The placement, again, I'd ask actual local professionals if you can. If the price of lumber weren't so astronomically high I'd actually rather suggest you build a dedicated listening room.
 
My only viewpoint is I've taken a disliking to audiophiles because they, for lack of a better term, snort their own farts. They don't actually care about the music, they buy into expensive bullshit, they look down on people with lesser systems, and when presented with actual facts they just cry. And they do shit like buy their own power poles and $100k speakers for their 250sq/ft apartment.
If you want to spend $10k, I can't stop you. All I'm trying to tell you is it would be better to get your room professionally treated, and if you aren't, then $10k on a simple stereo setup is pointless. Actual musicians, mixers, audiologists, electrical engineers, and recording engineers really don't like audiophiles.
 

Update:
 
MiniDSP recently released the MiniDSP Flex which seems to be based on the SHD platform.  Since you're not planning on using analog I would adjust as follows:
 
MiniDSP Flex MiniDSP Flex Dirac licence MiniDSP Umik-1 This will free up $550 - this can be used towards a few things:
 
Room Treatment:
 
Personally, I'm not sure you'll benefit that much from treatment.  The speakers have excellent off-axis properties by design and shouldn't have directivity issues that you'd want to absorb.  You're probably not having echo issues I imagine either.  It largely depends on whether the side that is not close to the wall has a reflection that creates a perceivable separate acoustic event or not.  If it does then you'll need treatment.
 
If you think you need acoustic treatment, you can get panels from GIK.  Since using dual subwoofers and DIRAC for bass issues, traps and broadband aren't really a bit deal.  The problem is without having the system in room to measure it's hard to tell, but thickness of a given panel should be 2" since bass isn't a concern for them.  Cost would range between $250-450 depending.
 
This will leave you with a bit towards stands/cables/rack/etc.
 
Subwoofers:
 
The other option is upgrading the subwoofers, but based on the size of room I'm not sure going to the 15" HSU line is particularly a good move.  Theoretically you could add more subs but I think that's likely overkill as well and might be hard to place.  Nonetheless this remains an option.
 
Exotic-ish Stands/Rack:
 
Probably the least advisable unless you think aesthetics are the finishing touch but possible.  There's some really neat looking stuff in this price range depending on taste.
 
 
ALTERNATIVE SYSTEM:
 
The above is the best passive system I could imagine for the amount given.  If one wanted to however go active . . .
 
2x Genelec 8341A - $6,000 Genelec 8341A SAM Subwoofer - $3,000 Genelec GLM 2.0 User Kit - $262 (Room Calibration) Genelec Wireless Volume Control for GLM - $60 Genelec Wired Volume for GLM - $110 Total: $9,432
 
This leaves ~$600 for room treatment, stands, etc.

My post was mostly a response to you (more or less) calling Dr. Floyd Toole an ignoramus - which is (more or less) akin to calling Bob Dobkin an ignoramus. If you don't know who Bob Dobkin is, look him up. You owe more to him than you realize. 
 
To make one thing clear, cumulative spectral decay (CSD) is an accepted and very useful measurement for loudspeakers. If you think a speaker stops producing sound the instant you stop applying a signal, you're wrong. There is energy stored in resonances in the drivers and in the cabinet itself, and it doesn't dissipate instantly. I'm not going to argue about this. If you think I'm wrong, by all means go over to DiyAudio or AudioScienceReview. Maybe you'll find a physicist with more patience than me.
 
Also, the other point I'm making is that EE is an extremely broad field. Microwave engineering and design of substations are both part of electrical engineering, but that doesn't mean that a typical power distribution engineer is in any way qualified to design microwave communications systems. Some might be, but the vast majority aren't. 
 
As for my last point, I mostly am suggesting that you don't use someone's college degree to argue that information from them is relevant. I know some really stupid people who managed to weasel their way through an EE program, and I know some extremely brilliant microwave engineers who never went to college.
 
 
What you've been doing for this entire thread is quoting (sometimes incompletely) a buddy who is supposedly a genius, but we have no idea who this is, and no useful information about why they're so qualified to give advice. What I do know is that what you're saying doesn't always make sense and isn't always correct.
 
Lastly, don't go thinking that there aren't some very smart engineers and scientists reading and replying to online discussion boards. Be careful who you call an idiot.  It's clear you have an anti-audiophile agenda, and it's clear that you think all audiophiles are stupid. You're achieving nothing productive by announcing it. You won't change the OP's mind. Most of what you'll do is annoy a lot of people and stop the thread from achieving anything productive.
 
Now for some useful advice to the OP:
 
I agree that you really should do some acoustic treatment before spending $10,000 on a system. I would advise the OP to do some research on acoustic treatment (there are plenty of excellent books and articles on the subject). Getting it 'pretty good' in a room of this sort isn't rocket science, and it can be done for well under $1000. You'll learn a lot more (and save a lot of money) learning how to do it yourself rather than hiring a professional.
 
I would not necessarily recommend the HS5 / HS8 monitors for pleasure listening. They're a decent speaker for what they cost, but they have their issues. They have some characteristics similar to the NS10s - another speaker that was wildly popular in recording studios, but which sound awful (and most recording engineers will agree with me on that). There are a lot of good loudspeakers in the $3,000 - $7,000 / pair range, both active and passive, and there are benefits to them over $500 monitors. 
 
Also, your room isn't terribly big. Depending on the speakers you buy, you may or may not benefit from a subwoofer. The V2108s I suggested, for example, will likely be just fine without a sub. Crossing over to a sub will improve the linearity of the mains, but depending on the mains this may or may not be noticeable. I find that with the V2108s, it isn't.
 
H-713
 
 

Like i said i'm perfectly happy atm with no urge to upgrade. I'm just interested in how audiphiles judge audio products. But so far it seems it's pretty much completely up to personal preference and online reviews offer little to no value other than basically ruling out duds.

Well, yeah. Diminishing returns is pretty subjective, and in a lot of ways measurements don't tell the full story of a certain audio product, and subjective revies can't usually be trusted (at least much) since the reviewer likely will have different ears, opinions, gear, ect. It's just something that you usually just determine for yourself, like... almost everything else in audio. sigh. While not really relevant to you, I do think that for ~90% of people getting into the hobby, a $200 stack such as the magni 3+/heresey and a modi should be good enough for whatever. $400-$500 for a stack is good for damn near anything, and anything more likely won't benefit you much in most cases. Just me, though. 
 
Forgot to answer this. Well, yes. First of all if they just have terrible __ (THD, SNR, whatever), a stack can sound pretty crappy with those artifacts. 
You can color the sound in a myriad of ways, cleaner measurements aren't the only answer. Tubes, for example are an easy example of this. Spec sheets and product sites are pretty bad offenders, though. In this day and age, getting a marginally cleaner dac/amp is basically pointless, nobody can hear the difference anyways (Whole topping lineup in a nutshell... lul)

Probably not what you're looking for but from a budget point of view, the razer kraken x lite are a really good set for the money. Great headphones. Great bass. Great highs. Great mic. I got these as a temp replaicment for a set that got wrecked. It was just supposed to be a cheap set to keep me going until i could affored something better but i've ended up stuck with these. They are the best bang for the buck you can get. They are also surround sound. It works very well during gaming. I'm a bit of an audiophile. I write my own music on pc. I use my headset for music and gaming. I have them plugged straight into my audio card. They just work and they do a great job for the money. I highly recomend them. I got mine on offer for £30 uk from amazon.

Just to add that i have a £400 5.1 surround speaker set and with this headset, i can hear more details than through the speakers. They are so much clearer and detailed. So this budget £30 headset is kicking the arse out my £400 speaker set.

Competitve gaming you say? You might wanna get a better headphone that can poinpont your most sworn enemies their foot steps before you're history.

DON'T TRUST THE RATINGS - YouTube

youtube reviews and personal experience are just not compareable. Be wary of all reviews honestly, unless that you know (through personal experience) that a reviewer has similar tastes as you. There's a lot of people that dont know what they're doing, there's some people that project false narritives, for one reason or the other.

Absolutely don't go for the z623, the speaker (and especially the sub) are quite crappy. I would recommend either the edifier 1280t, or the r1700bt (higher end bookshelf). 

Look at your local classifieds, there will very likely be some used powered studio monitors there from a respectable brand like Yamaha, KRK or Tannoy. These will almost always beat any consumer audio solution at a given price point.

DON'T TRUST THE RATINGS - YouTube

<-- Thread Locked -->
 
Please keep to a single thread for the same troubles. You can bump your post once every 24hrs until you receive the answer/solution need. 
 
 

Good lord there is a lot of arguing in this thread.
 
@Brok3n But who cares?If you want a speaker/subwoofer that sounds "fast" you just want a driver with low inertia/low weight. Any decent subwoofer is gonna have a stiff and light driver. SVS, JL Audio, REL, ADAM Audio, Genelec, Vandersteen, KS Digital, ZU Audio, Quested, Neumann, PSI Audio, Velodyne and Rythmik Audio are all good bets for subwoofers.
 
A subwoofer shouldn't really make everything rattle. Isolate the crap out of your loudspeakers. My favourite way to isolate loudspeakers is by using the IsoAcoustic pucks.
 
I can have my Martin Audio subs at full tilt in my listening room and have very little rattling occurring.
 
 
The room is the most important component of a system. I'd rather listen to a 1k system in a properly treated room instead of a 200k system in a crap room.
 
Put 250 dollars of your budget into Sonarworks. Get a calibrated measurement microphone. Get some good speakers, a good subwoofer, a good source, and calibrate them to your preferred target source. I've got my various pairs of monitors set to a flat profile, and my audiophile setup to a totally different target.
 
 
Personally, if I had 10k to get the best sound possible, I'd do this:
 
Two Neumann KH 310 D's for your main L/R loudspeakers. Incredibly accurate, very good transient response (what you call "fast"), plenty plenty loud enough and not too expensive.
 
A Genelec 7360 APM subwoofer. Hits 19Hz at -3dB, plenty of connectivity if you ever wanna go to 5.1 or 7.1, and loud enough.
 
A Solid State Logic 2 interface. Small, measures well and is backed by an extremely competent company, is also just genuinely extremely well made like other SSL kit. The volume also goes to 11.
 
A Sonarworks license. Learn to use the software. I'd also dig through REW's website to scratch up on loudspeaker measurement techniques.
 
A measurement microphone. The MiniDSP UMIK-1 is a very good bet.
 
Cables. Any old power cables will do, and then for signal just 2x 6.35mm TRS 3 pole to XLR 3 pole and 2x XLR to XLR. Just make sure the cables have good shielding, and are kept away from power cables, or cross them at 90 degrees. Cordial make some for about 15 USD each and they're very very good. You don't need expensive cabling.

Well I still think it's suboptimal and wouldn't put more than a grand into such a system. But it's your money.
 
Desk aside, what I would get with a 10k budget.... First set aside 10 to 15% of that for acoustic panels. Don't just get those cheap egg crate foams, they make proper diffusers for audiophiles that are also somewhat decorative. For speakers, since you said you're open to DIY solutions I'd definitely look into offerings from GR-Research or CSS Audio.  They're pretty similar sounding but GR errs on the side of more clarity as where CSS goes for more bass extension.  GR-Research options I think would work for you are: X-LS Encores, Dual X-CS centers, or NX-Studios. CSS: Chriton 1TDX or Criton 2TD-X MTM. And definitely max out on the components on which ever kit you get. Both companies offers kick ass subs, but GR uses servos so those are going to be faster and tighter. 
 
For powering them I'd either go for the Aegir/Freya combo, or something from PS Audio. You definitely want dual monoblocks and have them set up near the speakers to minimize the speaker cable length. 
 
As for dacs I think anything $500 and up should be good. I have a VMV D1se and it's quite nice. I also hear good think about Denafrips, but never heard one.  The HoloAudio stuff may be out of budget for you. (Sure they're less than 10K but you'd have to skimp on other areas and that just wouldn't be balanced. )