What will enhance sound the most that I can make myself and will cost less than $25-30?

This all depends on how you listen to your music.  If you use an iPod or other portable device then a DAC is probably not going to give you the best improvement.  If you do a ton of PC listening then a DAC will probably be worth investing in because PC audio is incredibly noisy.

The headphone you are using appears to get good reviews and the measurements make sense so you should not have to update your headphone for a while.

As for an amp it really depends on the amp.  I have experience with many amps and few amps deliver really great control of a dynamic or ortho like the HeadRoom amps.  The JDS labs O2 amp actually sounds pretty good for an introductory amp.

http://www.jdslabs.com/item.php?fetchitem=o2full

You could probably talk to them directly about acquiring a kit, but the price is a bit high for your budget.  You could always save up for a while and get the kit when you have the funds.  This way you will not have to upgrade again in a year or less.  I think the wait will be worth it.

It's not DIY, but a Sansa Clip+ has good sound, goes pretty loud, drives most phones, is a nice thing to have, and is nearly inside your budget. You need access to a computer to get tracks onto it, but you must have that if you can post here. It's probably the single best value-for-money hi-fi buy.

A Behringer UCA202 USB DAC/ADC is another cheap, good-value hi-fi item, drives most phones, maybe a bit quiet with some, works for recording too.

You can get a DAC kit pretty cheap on ebay if you want something to build, or this looks like a pretty good headphone amp:-

http://www.ebay.com/itm/Headphone-amplifier-DIY-KIT-ref-SOLO-supporting-for-Weiliangs-DAC3-DAC5-DAC7-/130815531517?pt=US_Amplifier_Parts_Components&hash=item1e753699fd

...only U$22 shipped. I haven't built one though, so that's a recommendation on sight only. Needs a power supply, batteries will do.

Watch out with the DAC kits, you usually need transformers to complete them.

These last 2 ebay items probably won't make that big a difference to the sound you get, but they provide a bit of entertainment to build.

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Most DAC kits also need an amplifier to drive headphones.

For $25 or so I would buy a set of Portapros or Sennheiser HD201. Variety is the spice of life and 2 headphones have more differences than all but the most extreme differences in amps or DACs. 

Man, you really aren't giving us much to work with. For $20 I would toss those Koss cans and trade up to Senn 202s. Then you could get a Behringer UCA202 for around $20 if you scope some eBay deals. Then for another $25-30 and you can find a decent Altoids-tin CMOY and you have a damn good super-entry level setup. But personally, I would just save up for a good set of cans. HD-25s or V-Moda M-80s or ATH-M50s ~$100-200. Even some Superlux 668/Samson SR-850 will give you some damn good bang/buck at around $50. And if you are a rock guy, look into Grados SR-60s or SR-80s for ~$70.

Save money and get better cans.

Those cans probaly wouldn't benefit much from an amp at all.

Your basically asking if racing tires and spoilers will "improve" your rusted out, 1992 Honda Civic.

Amps, DACs and cables(especially!!!) are very over-rated and exaggerated in audio;  Better SQ comes from better cans/speakers/IEMs.

Most onboard motherboard DACs are OK at best....I suppose you could get a DIY dac kit for $30 off ebay or a used Xonar card for $20(which has a headphone amp). Your ipod is fine for those headphones; I'd chuck the money towards better phones than a cmoy or sansa clip.

When you have decent phones; then it's worth blowing a $100-$200 on a better DAC and amp....even then, not all headphones benefit greatly from amps.

The O2 amp as a DIY project is close to being within your budget. It can be built for $50~$60 or even less if you shop carefully, omit the battery power option and do your own casing. Not my favorite amp, but very very hard to beat at it's DIY price point. Pre-built is too spendy for what it takes to build IMO. Very easy to build. 

For a cheap DAC project, I like the Grub DAC. Again not my favorite, but hard to beat for the price. Be aware that bare PCB DAC projects involve SMD soldering.  

If someone made a challenge for the best $100 total cost DIY system, my recommendation would be a Grub DAC hardwired to a AC only minimalist O2, both in a homemade case, driving Koss KSC75's with a headband mod. That has to be about the most bang-for-$ system going. I don't know about the DJ100's, but you're probably good there.

I would agree with others here in saying that the best bang for buck won't necessarily be a DIY improvement. For ~ $20 I would buy a set of KSC75s. Even with all of the other gear I own, I still enjoy the KSC75s straight out of my computer's on-board sound card.

In my opinion, you will get noticeable improvements with better headphones straight out of almost any source these days. System improvement is about addressing bottle-necks in your system. Up until maybe the $300 dollar range (speculating), you headphones are the weakest link.

By all means build a DIY CMOY - many of us started that way - but don't expect sonic improvements. It will make your music louder, but it won't make it necessarily sound better.

PS. I haven't hear the headphone you currently have, so I have no idea whether the KSC75 is better.

Quote:

Originally Posted by badhomaks 

I don't understand the hate for Koss though. They are great quality cans and receive high reviews from many different people. Just because it doesn't have sennheiser or stax in its name doesn't make it bad. Yes Koss aren't known for super high quality headphones but that doesn't mean that they don't release gems once in a while. 

(Although if you're comparing these ~$50 cans with something that costs >$110, obviously headphones that are 2x, 3x the price will probably sound better.)

 

What's it with you people belittling my cans? Thank you NA Blur, nikongod and wakibaki for not telling me to throw away my headphones like they're ****.

It's moreso the fact you want buy "improvements" like a new DAC and amp.
Everybody is pointing out you should save your money and get something new in the $100-$150 range if you want "better".

The Koss ain't bad but your only $50-$100 away from "awesome" instead of "nice".

Quote:

Originally Posted by badhomaks 

I don't understand the hate for Koss though. They are great quality cans and receive high reviews from many different people. Just because it doesn't have sennheiser or stax in its name doesn't make it bad. Yes Koss aren't known for super high quality headphones but that doesn't mean that they don't release gems once in a while. 

(Although if you're comparing these ~$50 cans with something that costs >$110, obviously headphones that are 2x, 3x the price will probably sound better.)

 

What's it with you people belittling my cans? Thank you NA Blur, nikongod and wakibaki for not telling me to throw away my headphones like they're ****.

No-one is telling you that they're ****. Perhaps you could try being a little less precious. Maybe when you ask for advice you could actually take those suggestions on board for what they are, suggestions in response to your request for help - everyone is trying to help. Otherwise, you may spend your $30 and end up without any audio improvement. But, you may have learnt the exact same lesson that the rest of us are attempting to pass on to you... for free.

I have plenty of headphones in the sub $100 category. Almost without exception, they are bettered by more expensive (proper) headphones. Apart from Bose, Skullcandy, Dr Dre and other crappy lifestyle brands, more money does usually buy you better cans.

And, for the record, I have nothing against any (proper) brand of headphones. I recommend the Koss KSC75 to anybody who will stand still - they are a bargain. And, I regularly stand them against headphones many times their price. I am listening to mine right now.

Quote:

Originally Posted by bada bing 

The O2 amp as a DIY project is close to being within your budget. It can be built for $50~$60 or even less if you shop carefully, omit the battery power option and do your own casing. Not my favorite amp, but very very hard to beat at it's DIY price point. Pre-built is too spendy for what it takes to build IMO. Very easy to build. 

 

disagree. 

The prebuilt prices on the O2 and most DIY-for-profit amps are about perfect if you consider a reasonable rate for hourly labor, and the fact that the buyer assumes no risk of failure and does not have to buy any tools which he may not own. 

Have you ever built an amp for BOM cost? I have not.

Continuing the funny accounting that says that you can build an O2 for $50, If you count parts that any long-term-DIYer already has in his parts bin an O2 can be built for even less than $50. I suspect I could put one together for the cost of the PCB. 

Quote:

Originally Posted by badhomaks 

I don't understand the hate for Koss though.

Not only were you commended to look at Koss' KSC75 twice, you also got a recommendation for Koss' PortaPros. Both are essentially the same driver, but they sound a bit different due to the difference in the way they sit on your ear.

I've owned both and prefer the PortaPros, but I've got enough gray in my beard that démodé styling isn't a problem for me.

I haven't seen any "hate" here, in fact, but there is strong negative sentiment against "DJ" style headphones in general here on Head-Fi. That's because they tend to favor sound isolation and bass heaviness over accuracy and agility. Sound isolation and strong bass are nice in their place, but as a rule, accuracy and agility are more highly valued here.

So, take it from the guy offering you the CMoy project: nikongod is right. You'll hear a bigger difference from a KSC75 or PortaPro than by building any amp, CMoy or no.

Not that building a CMoy pocket amp isn't worthwhile in its own right.  You'll get a lot more out of the experience than just improved sound.