[iNeedCansBad]

Hello, I'm looking to build my own 2.1 computer system.   I currently have Klipsch 2.1 Promedia's, and while they sound good the bass bottoms out far too easy, and there aren't much mids at all.   I had KRK Rokit 8's with 10" sub and I think I still have a pretty good ear coming from those days.  It just seems like no company makes a great 2.1 configuration.   My issue is figuring out how to power the setup I want.   I'm looking at this device, Nobsound TPA3116D2.  It seems to be able to drive a 2.1 system, but to what extent?  
 
I want to power two 6" full range speakers, and one 6" subwoofer? Or am I asking too much?  Could I also wire in tweeters? I have some speakers in mind such as the Dayton Audio RS150P-4 6", and Dayton Audio DCS165-4 6-1/2".   Again this is just quick research from me, and I'm really looking for some help here for my project goals.  The woodworking is the easy part, the hard part is figuring out the configuration, and components that will satisfy my needs.  All help appreciated.

 

[ProtegeManiac]

  Hello, I'm looking to build my own 2.1 computer system.   I currently have Klipsch 2.1 Promedia's, and while they sound good the bass bottoms out far too easy, and there aren't much mids at all. 

 

That's because these are tiny drivers that rely on cutting the subwoofer (which is still designed as a subwoofer) cut high enough to catch the roll off on the drivers.
 

  It just seems like no company makes a great 2.1 configuration.

 

That's because the usual target market for 2.1 speakers are those who just want some sound coming out of their computers but with bass, not necessarily audiophiles. That said, it's not like none of them thought of doing that at all.

https://www.amazon.com/Swans-Powered-Bookshelf-Speakers-Subwoofer/dp/B002TG3B7C/ref=sr_1_1?s=electronics&ie=UTF8&qid=1490149052&sr=1-1&keywords=HiVi+M50W
 
 

  My issue is figuring out how to power the setup I want.   I'm looking at this device, Nobsound TPA3116D2.  It seems to be able to drive a 2.1 system, but to what extent?  

 
Assuming the power ratings are within honest and reasonable distortion and noise levels, 50w x 2 + 100w is a lot for any speaker with reasonable efficiency.
 

 
I want to power two 6" full range speakers, and one 6" subwoofer? Or am I asking too much?  Could I also wire in tweeters? 

 

You can use tweeters but you'd need to wire up a passive crossover. And speaking of crossovers, that amp you put in doesn't seem to have one, so now you have to make a passive crossover for the subwoofer too.

 

Honestly for that kind of effort, I'd at least just get a regular 2ch amp and use a subwoofer with high level inputs. At least then you'd have a subwoofer plate amp that has a variable crossover so you can tune it to match the in-room response of the speakers rather than relying on just the T/S parameters and then end up having to put so much effort in changing the low pass crossover settings.

 

Also to make these easier I'd get 2-way speaker kits that already come with passive crossovers. And even if you make the sub yourself also, get a plate amp that has a variable crossover.
 

 
I have some speakers in mind such as the Dayton Audio RS150P-4 6", and Dayton Audio DCS165-4 6-1/2".   Again this is just quick research from me, and I'm really looking for some help here for my project goals. 

 
 

One other way to do this, in case you're up to making the passive crossovers yourself anyway, is to use two subs not powered independently. In other words, just make two standmount/desktop cabinets with one FR and one subwoofer in it, that way you can design the crossover based on T/S parameters and driver specs, since you'd have nearly no need to have a variable crossover in order to tune the system for time alignment. Normally you'd have to use a variable crossover in order to get to the sweet spot where the sub's response catches where midwoofers/FR drivers start rolling off while not being too high as to make the sub easy to localize. Having the subwoofers and their ports on the same cabinet as the midwoofers/FR drivers can minimize that, but of course you'd need to construct the cabinets in such a way that these drivers will be smack next to each other.

 

The problem with his approach though is that this will also make the cabinets larger, so if you're thinking of using these as desktop speakers, that can be a problem. At best, you'd have to design the interior of the cabinet to be as compact as possible for the subwoofer (put the midwoofer/FR driver in an isolated and sealed chamber to simplify the design), and then carefully package the slot port like a maze snaking along the interior of the case. 

 

Alternately, you can also use smaller drivers, which would be ideal as far as the FR driver is concerned. The 4in version of those Daytons for example are rated up to 20,000hz (although AFAIK it's effectively rolling off at just past 10,000hz), so the 6in rated up to 10,000hz could be rolling off before that. These are more appropriately extended range midwoofers, not anywhere near being fullrange. Best case scenario, you need a supertweeter, like those you see mounted on the top of speakers that use Fostex FR drivers, but then that again complicates the crossover design, and having a 3-way config on a desktop system can be problematic for time alignment. You can look into TangBand - AFAIK they have a 3in (sub)woofer driver to match 3in FR drivers in 2-way cabinets. Or pair a Dayton 3in or 4in FR driver (or TB 3in or 4in) with a 5in or 6in (sub)woofer.

 

If this isn't for desktop/nearfield use, and you can sit around 1.5m away at least, this gets easier. You can design tower speakers instead, basically aligning the position of the FR driver to how high your head will be when seated, making sure the supertweeter and (sub)woofer drivers are smack next to it (this would likely mean a deep enclosure front to rear if you'll have the FR driver in an isolated chamber). Alternately, you can also use different size drivers just to minimize the need for the supertweeter, like a 4in FR driver with a 5in or 6in (sub)woofer, the former in a sealed, isolated chamber and the latter in a large, transmission line chamber.

 

The entire interior doesn't need to be entirely an air chamber for the drivers either, since the cabinets will be larger front to rear it can give a lot of space for the (sub)woofer that it doesn't take up all the space top to bottom. Isolate extra space at the bottom  and then massload that chamber with very dry sand, or maybe tightly packed ball bearings, to stabilize the cabinet.

 

[iNeedCansBad]

Please forgive me, I don't understand everything you've just said.  I'm not great with the technical details.     Can you explain using a 2 channel amp, and using a subwoofer with high level inputs? I don't understand high level inputs, or how I would connect it all.  
 
Do you mean getting a plate amp like the Dayton Audio SA100 and wire the inputs into the subwoofer plate amp, and out to the two channel amp and then to my speakers? 
 
Again, I apologize, but I am new to this world.  I've wired up crossovers on my car, but they were basically plug and play.  I've done some electrical repairs in my day, but never soldered a crossover or anything like it.   

 

[ProtegeManiac]

  Please forgive me, I don't understand everything you've just said.  I'm not great with the technical details.  Can you explain using a 2 channel amp, and using a subwoofer with high level inputs? I don't understand high level inputs, or how I would connect it all.  

 

High level input is an input that can take an amplified signal. Like car audio integration processors that take the signal from the stock amplifier (and then uses correction EQ later) or subwoofer plate amplifiers with speaker wire input (and output) terminals.
 

 
Do you mean getting a plate amp like the Dayton Audio SA100 and wire the inputs into the subwoofer plate amp, and out to the two channel amp and then to my speakers? 

 

No, using high level inputs on the subwoofer means it will be source to 2ch amp to subwoofer to speaker. Speaker wire from the amp will go to the sub, then speaker wire from the sub to the speakers. That doesn't affect the speakers' sound, but it works like preamped sub outputs since the volume control on the amp works on the signal going into the sub. Therefore when you change the volume on the stereo amp the sub changes output level along with it.

 

That said, if you use the SA100, it has low level connections - both input and simultaneous output - so you can use that too. That of course assumes I'm using a dedicated preamp with a separate power amp, because if you wire it up as source (DAC, CDP, DAP, TT) to subwoofer to 2ch amp to speakers, the preamp on the stereo amp does not affect the subwoofer. That means that every time you change the volume on the 2ch amp, you'd have to reach over to the subwoofer to change the gain there to match what you just did with the mains.

 

You can clearly see what's labelled as "high" and "low" level here.

 
 

 
Again, I apologize, but I am new to this world.  I've wired up crossovers on my car, but they were basically plug and play.  I've done some electrical repairs in my day, but never soldered a crossover or anything like it.   

 

And that's the thing - speakers either come as finished products or kits that have crossovers. Or as in some options you've put forth, you'd have to design and make the crossovers (at the simplest, an inline resistor or notch filter, or make a circuit on a breadboard) or have someone make them for you, but still the settings aren't all that variable. This doesn't matter as much between the midwoofer and the tweeter especially if they came in a kit, but if you'll use a 2.1 amplifier and no way to have a variable low pass on the sub (or worse, no low pass filter), you'd have no capacity to easily tweak the system.

Think of this as being in your car and you have to solder on capacitors and such as opposed to twisting a knob on the subwoofer amp or hitting a few buttons on your receiver-processor whenever the sub is playing too much of the mids that it's pulling the bass to the rear or too little that you barely hear it much less reinforce what the midwoofer can't play.

 

If you make fullrange mains you'll only need the subwoofer low pass filter, so at the very least, I'd avoid that Nobsound 2.1ch amp and just go with a 2ch amp and a sub with a plate amp.

 

[iNeedCansBad]

Thanks again.  Clearly I've got a lot to learn.    Now let me ask you this, what 2 channel amp and sub plate amp would you go with if you were to build a 2.1 system? And what speakers would you go for?  I obviously have a budget to keep in mind, lets say $300.  I rather have someone like yourself steer me in the right direction of components opposed to just picking my own with my limited knowledge.   As far as the desktop speakers are concerned I'd like to get at least 4" with tweeters, and a subwoofer that can handle deep bass without bottoming out.

 

[DelsFan]

  Hello, I'm looking to build my own 2.1 computer system.   I currently have Klipsch 2.1 Promedia's,
 
I want to power two 6" full range speakers, and one 6" subwoofer? Or am I asking too much? 

 
I don't know as much as most people here.  You don't state what equipment you currently have other than a (presumably) desktop computer and the Klipsch speakers.  But the answer to your last question could be, "Yes, you are asking too much for a near-field computer desk speaker setup."
 
My first question is, what are you currently using to convert the digital signal from the USB port of your computer to analog, in order to send it to your speakers.  If you are using a $29.95 Behringer unit like I have in my kitchen, then you might experience a large (and satisfactory) improvement by upgrading to a quality DAC with a USB input (and perhaps MQA decoding capability), along with a good USB cable (more than $10/meter, less than $300/meter).  And the solution would be simple.  
 
If you could find a friend (or a friend's Dad) who has a $200 to $1000 DAC you could borrow (one with a USB input though), something like the Schiit Modi Uber or Multibit, or Bifrost (regular flavor or Multibit) you would learn whether or not the simple addition of a good DAC* would offer a quick and easy and satisfactory solution.
 
* Use a good USB cable, if only the $15 Belkin Gold.  And in order to see if your Klipsch speakers can be satisfactory - or not - also use a decent pair of RCA interconnects to go from your DAC's output to your speaker input.  You don't have to buy them, or you can keep your eye out for a used pair.  But using the $2.00 interconnects that come with your XBox won't tell you if you could be satisfied with the speakers you have, or not.)
 
I'm a big fan of overkill - so if you want to purchase a DAC and amplifier (or combo unit) and speakers that don't have their own built-in amplifier, then more power to you.  My belief is that in order to put together a system that would be better than spending $50 on a USB cable and $149 or $249 on a Schiit Modi2 Uber or Modi2 Multibit, and $30 on a used pair of formerly $75/2 meter pair RCA interconnects, and keeping your present speakers (so, a $200 to $300 expenditure), you would have to spend:
 
USB cable  $30
cheap DAC   $99  for Schiit's least expensive offering of the Modi 2, which may be plenty sufficient
interconnect  $30
Amplifier     $200?  can you buy something for $200 that is any good?  Can you buy a DAC/amp for $200?  Maybe you can.
Speakers   $129/pair for the Pioneer SP BS-22 
or               $229/pair for the Elac Debut B5
 
You still don't have a subwoofer or crossovers and the tally is already in the $360 to $460 range.
 
You might end up going with bookshelf speakers and a subwoofer find a "good" DAC/amplifier powerful enough to power them.  But I'd try and borrow someone's DAC and some better-than-junk cables and interconnects, and see what that does for your existing Klipsch speakers first.

 

[sarge7359]

The Pioneer SP BS-22 are supposedly really nice, but I dunno about nearfield.

The Swan system referenced above is prolly about right overall: https://www.amazon.com/Swans-Powered-Bookshelf-Speakers-Subwoofer/dp/B002TG3B7C/ref=sr_1_1?s=electronics&ie=UTF8&qid=1490149052&sr=1-1&keywords=HiVi+M50W
and it is made for computer audio as opposed to full room audio.

 

[iNeedCansBad]

   
I don't know as much as most people here.  You don't state what equipment you currently have other than a (presumably) desktop computer and the Klipsch speakers.  But the answer to your last question could be, "Yes, you are asking too much for a near-field computer desk speaker setup."
 
My first question is, what are you currently using to convert the digital signal from the USB port of your computer to analog, in order to send it to your speakers.  If you are using a $29.95 Behringer unit like I have in my kitchen, then you might experience a large (and satisfactory) improvement by upgrading to a quality DAC with a USB input (and perhaps MQA decoding capability), along with a good USB cable (more than $10/meter, less than $300/meter).  And the solution would be simple.  
 
If you could find a friend (or a friend's Dad) who has a $200 to $1000 DAC you could borrow (one with a USB input though), something like the Schiit Modi Uber or Multibit, or Bifrost (regular flavor or Multibit) you would learn whether or not the simple addition of a good DAC* would offer a quick and easy and satisfactory solution.
 
* Use a good USB cable, if only the $15 Belkin Gold.  And in order to see if your Klipsch speakers can be satisfactory - or not - also use a decent pair of RCA interconnects to go from your DAC's output to your speaker input.  You don't have to buy them, or you can keep your eye out for a used pair.  But using the $2.00 interconnects that come with your XBox won't tell you if you could be satisfied with the speakers you have, or not.)
 
I'm a big fan of overkill - so if you want to purchase a DAC and amplifier (or combo unit) and speakers that don't have their own built-in amplifier, then more power to you.  My belief is that in order to put together a system that would be better than spending $50 on a USB cable and $149 or $249 on a Schiit Modi2 Uber or Modi2 Multibit, and $30 on a used pair of formerly $75/2 meter pair RCA interconnects, and keeping your present speakers (so, a $200 to $300 expenditure), you would have to spend:
 
USB cable  $30
cheap DAC   $99  for Schiit's least expensive offering of the Modi 2, which may be plenty sufficient
interconnect  $30
Amplifier     $200?  can you buy something for $200 that is any good?  Can you buy a DAC/amp for $200?  Maybe you can.
Speakers   $129/pair for the Pioneer SP BS-22 
or               $229/pair for the Elac Debut B5
 
You still don't have a subwoofer or crossovers and the tally is already in the $360 to $460 range.
 
You might end up going with bookshelf speakers and a subwoofer find a "good" DAC/amplifier powerful enough to power them.  But I'd try and borrow someone's DAC and some better-than-junk cables and interconnects, and see what that does for your existing Klipsch speakers first.

Wow.  This is getting more and more confusing.  That's a lot of info.  DAC units are completely new to me, I know nothing about them.  I have my Klipsch Promedia 2.1's hooked up simply to to the motherboards 3.5mm jack.  I thought DAC's were primarily used with headphones, so I never gave them much thought as I don't use headphones anymore.  I also don't see a way to hook the Klipsch up to the DAC's mentioned without adding multiple cables and complicating the setup.  
 
As far as speakers are concerned, my tv audio speakers are Sony SSCS5 which were rated comparable to the Pioneer's mentioned when I bought them. I can test them on any set up, or perhaps use them as my desktop speakers down the line and get something different for my TV audio.   I've always been interested in the "Overnight Sensations" personally.  

 

[ProtegeManiac]

  DAC units are completely new to me, I know nothing about them.  I have my Klipsch Promedia 2.1's hooked up simply to to the motherboards 3.5mm jack.  I thought DAC's were primarily used with headphones, so I never gave them much thought as I don't use headphones anymore.  I also don't see a way to hook the Klipsch up to the DAC's mentioned without adding multiple cables and complicating the setup.  

 

DAC is Digital to Analogue Converter. Everything that plays digital audio from somewhere (CD, ripped files, streaming, etc) all have some kind of DAC in it, otherwise 10001001010100101110010000100 music data can't be converted to an analogue electronic signal that will then be amplified to a signal strong enough to "drive," ie, move a transducer like speakers or headphones.

 

Note that in some cases the DAC and amp can be built into the same chassis sharing a power supply or have two power supplies in it for each circuit, or in some cases, the DAC stage is powered via USB.
 

  Wow.  This is getting more and more confusing.

 

I'd just focus on building the speakers first.
 

  Now let me ask you this, what 2 channel amp and sub plate amp would you go with if you were to build a 2.1 system? And what speakers would you go for?  I obviously have a budget to keep in mind, lets say $300.  I rather have someone like yourself steer me in the right direction of components opposed to just picking my own with my limited knowledge.   As far as the desktop speakers are concerned I'd like to get at least 4" with tweeters, and a subwoofer that can handle deep bass without bottoming out.
 

 

Stereo amplifier

http://www.parts-express.com/dayton-audio-dta-120-class-t-mini-amplifier-60-wpc--300-3800

 

Subwoofer plate amp

http://www.parts-express.com/dayton-audio-sa100-100w-subwoofer-plate-amplifier--300-802

 

Fullrange drivers

http://www.parts-express.com/dayton-audio-rs100-8-4-reference-full-range-driver--295-35

or

http://www.parts-express.com/tang-band-w4-1320sif-4-bamboo-full-range-speaker--264-914

 

Subwoofer
http://www.parts-express.com/tang-band-w6-1139sif-6-1-2-paper-cone-subwoofer-speaker--264-919
 
I picked the 6.5in subwoofer under the assumption that space is a premium. That Tang Band sub can use less internal air volume than the competing Dayton for not a lot more money, so when you design the box, take the following into account:
 
1. Internal air volume (go with the vented box), including port volume and flared end on the port
2. Box shape for where you want to put it (ie slimmer, taller, wider, etc - never make a perfectly square box either)...
3. ...but don't forget that the plate amp (and subwoofer driver) mounting requirements

 

As for the fullrange drivers, since you're using a sub anyway, no need to build a large and complex cabinet to extend its frequency response. As long as the vented box can comfortably get it to 100hz if not a bit lower, just cut the sub a little higher. If possible, design the sub box to fit somewhere between the two speakers and at the same height (ie on the desk) so localization will be minimized (more accurately, that you can cut it a little higher than you usually can).

 

Use the motherboard's FL+FR output to feed the stereo amp, and run its speaker cables to the sub then the speakers.

 

If you want to try a DAC, connect it to the motherboard's USB or SPDIF, then run a cable from its line out to the speaker amp.

 

[sarge7359]

Wow, the parts list from ProtegeManiac plus a few cables, couple passive crossovers, some wire and some know-how on creating enclosures would get you a pretty good overall system for about $350. 
 
Or get the pre-packaged thing but it won't be nearly as good.

 

 

[DelsFan]

  Wow.  This is getting more and more confusing.  That's a lot of info...    I also don't see a way to hook the Klipsch up to the DAC's mentioned without adding multiple cables and complicating the setup.  

 
I steered you wrong (too high-end) originally.  Other than the Schiit Modi2 Uber, whereupon you'd just need one RCA to 1/8" jack Y-adapter. Although I wasn't suggesting you purchase a DAC, only borrow a decent one and see if that one purchase would make you a LOT happier with your Klipsch speakers.  I can assure you, the Modi2 Uber or either of the Audioquest versions below would be a major leap over the DAC in your laptop.
 
Here are three low-cost (ish) and easy solutions in addition to the modi2 Uber.  The Dragonfly Red I believe is able to receive a firmware update for MQA (Tidal Hi-Res decoding) if that matters to you.  Both Audioquest items are recommended in high-end audiophile magazines.  I'm going to try the Dragonfly Red myself in the next week.
 
I just tried this cheap Behringer "DAC" (was in use elsewhere in the house) and it is a slight but noticible improvement with my desktop speakers (over using 1/8" jack in back of computer).
https://www.amazon.com/Behringer-U-Control-Ultra-Low-Interface-Software/dp/B0023BYDHK/ref=sr_1_2?ie=UTF8&qid=1490488469&sr=8-2&keywords=behringer+uca+202
 
 
I'll be ordering the second one of these, this weekend:
https://www.amazon.com/gp/product/B01DP5JHHI/ref=s9_dcacsd_dcoop_bw_c_x_1_w
 
https://www.amazon.com/dp/B01DFMV4NQ?psc=1&smid=A1FEN8WPYFT9YE

 

[ProtegeManiac]

   
I steered you wrong (too high-end) originally.  Other than the Schiit Modi2 Uber, whereupon you'd just need one RCA to 1/8" jack Y-adapter. Although I wasn't suggesting you purchase a DAC, only borrow a decent one and see if that one purchase would make you a LOT happier with your Klipsch speakers.  I can assure you, the Modi2 Uber or either of the Audioquest versions below would be a major leap over the DAC in your laptop.
 
Here are three low-cost (ish) and easy solutions in addition to the modi2 Uber.  The Dragonfly Red I believe is able to receive a firmware update for MQA (Tidal Hi-Res decoding) if that matters to you.  Both Audioquest items are recommended in high-end audiophile magazines.  I'm going to try the Dragonfly Red myself in the next week.
 
I just tried this cheap Behringer "DAC" (was in use elsewhere in the house) and it is a slight but noticible improvement with my desktop speakers (over using 1/8" jack in back of computer).
https://www.amazon.com/Behringer-U-Control-Ultra-Low-Interface-Software/dp/B0023BYDHK/ref=sr_1_2?ie=UTF8&qid=1490488469&sr=8-2&keywords=behringer+uca+202
 
 
I'll be ordering the second one of these, this weekend:
https://www.amazon.com/gp/product/B01DP5JHHI/ref=s9_dcacsd_dcoop_bw_c_x_1_w
 
https://www.amazon.com/dp/B01DFMV4NQ?psc=1&smid=A1FEN8WPYFT9YE

 
His problem is really more in the speakers themselves as he described in the OP... 

Originally Posted by iNeedCansBad /img/forum/go_quote.gif
  Hello, I'm looking to build my own 2.1 computer system.   I currently have Klipsch 2.1 Promedia's, and while they sound good the bass bottoms out far too easy, and there aren't much mids at all.   I had KRK Rokit 8's with 10" sub and I think I still have a pretty good ear coming from those days.  It just seems like no company makes a great 2.1 configuration.   My issue is figuring out how to power the setup I want.   I'm looking at this device, Nobsound TPA3116D2.  It seems to be able to drive a 2.1 system, but to what extent?  
 
I want to power two 6" full range speakers, and one 6" subwoofer? Or am I asking too much?  Could I also wire in tweeters? I have some speakers in mind such as the Dayton Audio RS150P-4 6", and Dayton Audio DCS165-4 6-1/2".   Again this is just quick research from me, and I'm really looking for some help here for my project goals.  The woodworking is the easy part, the hard part is figuring out the configuration, and components that will satisfy my needs.  All help appreciated.

 
...then I explained how it was the problem here.

Originally Posted by ProtegeManiac /img/forum/go_quote.gif
 

That's because these are tiny drivers that rely on cutting the subwoofer (which is still designed as a subwoofer) cut high enough to catch the roll off on the drivers.
 

That's because the usual target market for 2.1 speakers are those who just want some sound coming out of their computers but with bass, not necessarily audiophiles. That said, it's not like none of them thought of doing that at all.

https://www.amazon.com/Swans-Powered-Bookshelf-Speakers-Subwoofer/dp/B002TG3B7C/ref=sr_1_1?s=electronics&ie=UTF8&qid=1490149052&sr=1-1&keywords=HiVi+M50W

...

 

[iNeedCansBad]

   

DAC is Digital to Analogue Converter. Everything that plays digital audio from somewhere (CD, ripped files, streaming, etc) all have some kind of DAC in it, otherwise 10001001010100101110010000100 music data can't be converted to an analogue electronic signal that will then be amplified to a signal strong enough to "drive," ie, move a transducer like speakers or headphones.

 

Note that in some cases the DAC and amp can be built into the same chassis sharing a power supply or have two power supplies in it for each circuit, or in some cases, the DAC stage is powered via USB.
 

 

I'd just focus on building the speakers first.
 

 

Stereo amplifier

http://www.parts-express.com/dayton-audio-dta-120-class-t-mini-amplifier-60-wpc--300-3800

 

Subwoofer plate amp

http://www.parts-express.com/dayton-audio-sa100-100w-subwoofer-plate-amplifier--300-802

 

Fullrange drivers

http://www.parts-express.com/dayton-audio-rs100-8-4-reference-full-range-driver--295-35

or

http://www.parts-express.com/tang-band-w4-1320sif-4-bamboo-full-range-speaker--264-914

 

Subwoofer
http://www.parts-express.com/tang-band-w6-1139sif-6-1-2-paper-cone-subwoofer-speaker--264-919
 
I picked the 6.5in subwoofer under the assumption that space is a premium. That Tang Band sub can use less internal air volume than the competing Dayton for not a lot more money, so when you design the box, take the following into account:
 
1. Internal air volume (go with the vented box), including port volume and flared end on the port
2. Box shape for where you want to put it (ie slimmer, taller, wider, etc - never make a perfectly square box either)...
3. ...but don't forget that the plate amp (and subwoofer driver) mounting requirements

 

As for the fullrange drivers, since you're using a sub anyway, no need to build a large and complex cabinet to extend its frequency response. As long as the vented box can comfortably get it to 100hz if not a bit lower, just cut the sub a little higher. If possible, design the sub box to fit somewhere between the two speakers and at the same height (ie on the desk) so localization will be minimized (more accurately, that you can cut it a little higher than you usually can).

 

Use the motherboard's FL+FR output to feed the stereo amp, and run its speaker cables to the sub then the speakers.

 

If you want to try a DAC, connect it to the motherboard's USB or SPDIF, then run a cable from its line out to the speaker amp.

Great info again.  I've bookmarked everything, and I'll be making an order within a few weeks.  I'm trying to figure out what size/shape of box I should make for the full range Dayton's.  Any advice appreciated.  Since space isn't a concern I'll go with the Dayton subwoofer as well.

 

[ProtegeManiac]

  Great info again.  I've bookmarked everything, and I'll be making an order within a few weeks.  I'm trying to figure out what size/shape of box I should make for the full range Dayton's.  Any advice appreciated.  Since space isn't a concern I'll go with the Dayton subwoofer as well.

 
Just take into account the space where you'd want the speakers to be first, that determines the general shape or even the area of the top and bottom panels.
 
As for the box type, since you have a sub, no need for anything fancy. Just go with the recommended ported box and port dimensions in the manual.

 

[DelsFan]

   
His problem is really more in the speakers themselves as he described in the OP... 
 
...then I explained how it was the problem here...

 
I understand, and the advice you've given is great.  Though ultimately the system the OP is discussing will cost more than his stated budget of $300.  AND, it doesn't matter how much he spends on a new speaker system, which might actually be what he wants and needs, if he utilizes the (lowest quality available) analog signal from the 1/8" speaker output on the back of his desktop/laptop instead of outputting a digital through his USB jack (which leads to the subsequent expenditure for an outboard DAC) he's still pissin' in the wind.  
 
That's why I suggest the first step would be the fact finding mission of borrowing someone's $99 to $500 DAC just to see:
a) what, if any, difference any a USB DAC makes with his Klipsch speakers, and
b) whether or not he'd then rather purchase the DAC first - and, if the sound is better, utilize the then more listenable Klipsch speakers he already owns while "beating the system" by building his own speakers.
 
It won't take the OP more than two or three minutes (including the time to switch between output methods) listening to 30 seconds of a well-recorded track from a lossless file to tell if I am steering him right.  If using his USB port and an outboard DAC is significantly better, it will be obvious right away.  Lot's more detail, tighter bass, less mush.  Or maybe it won't make any difference.
 
I'll bow out here as the OP is in better hands than mine as he plots his speaker strategy.  He just needs to find out, in his situation, is an outboard DAC a necessity as I'm suggesting, or if is it not.