I think OP can get pretty good results using the equipment he has now. He has the PC for dsp, he has the dac channels, has the amp channels. As Pashka said, what he's really lacking is woofers. Forget subwoofers, he needs just regular bass drivers. I think even the Edifiers would be a good improvement because they would at least have woofers in the same cabinet and not, like, below the desk or wherever the jbl sub is situated.
The jbl is just a single 8". In my opinion, it is
not worth spending the limited funds on new amplifiers or bookshelf speakers. If you buy active speakers, you're still paying for the amps inside those.
If I were you I would hunt for a great deal on something used in your local area. Otherwise, I would spend
all the small budget on two bass modules for the speakers you already have.
The Rockits are good quality speakers but will cost more. They are $320 each, $640 for a pair, and I don't know if that includes shipping. I'm sure many members here with deeper pockets than me will disagree, but it is a lot to spend and still need a subwoofer. Many people do find them worthwhile, of course.
By the way, if you buy new active speakers, there is no need to switch between them and the old surround setup. You can use the analog outputs from your motherboard, connecting the new active speakers to that, and connecting the Onkyo reciever also for the other channels, just adjust the volume using your PC. Using PC gives you a lot of flexibility to mix and match different amps and speakers. So if you do go that route, you don't have to give anything up.
Yeah, I am going into some technical detail here, but I think it is a good learning opportunity if you want to look at it that way. What I'm suggesting is a janky setup that takes more involvement from the user and is limited to PC use only, however, it will make the most of your money and get better sound quality for cheap. What I'd do is combine bass speakers with the small speakers you already have, such that each pair functions as a single bigger speaker. Within the price range of a few hundred bucks, you can achieve better sound by using what you have effectively, getting good deals on used parts, and especially making your own cabinets that can be bigger and/or better than commercial offerings in your price range. There are just some things you need to learn, and they can benefit you throughout the rest of your audio journey.
Starting off, the optical cable has the advantage of electrical isolation from the computer, so it sends a perfectly clean digital signal. That signal is limited to only PCM audio 2 channels (left and right) unless you bitstream a compressed format like DTS or Dolby to the reciever. Often PC games do not output such a compressed format, so using the optical cable you can have surround sound on movies but not for games or other applications that require more uncompressed audio channels. So in 2-channel usage, optical is the ideal connection, but in surround sound the quality is compromised by a lossy codec.
There is nothing wrong with analog audio cables, but it's possible the analog output from a PC could introduce more electrical noise from the PC into the amp. This depends on the quality of your PC or soundcard though. I use the analog output from my PC every day with a very similar reciever to yours and it is not a problem at all. Nothing really is lost; but possibly more noise is added, and in most cases this is inaudible. Either your PC or the reciever must convert the digital audio to analog before it is amplified, and who's to say which does a better job.
The reason why you want to use your analog output to the Onkyo is to have all 6 channels of output available. There are 3 stereo jacks on the back of your PC for the left, right, center, subwoofer, surround left, and surround right channels. With this, the PC can control each of the amplifiers in your reciever separately. We need at least 4 channels, for your left and right speakers, and your left and right bass modules. Optical isn't suitable for this. So you connect the PC to the Onkyo amp with 3 of these 3.5mm to RCA cables and select the multichannel input on the reciever. Now you can have surround sound in games, you can get the full quality from Dolby TrueHD and DTS Master Audio.
Next, you use an excellent free program called EqualizerAPO that lets you apply processing to all of the audio that comes out of your PC. There are many guides to using it online. You have to set up all the filters manually, but it is one of the best things to improve sound quality for everything on your computer.
Inside most speakers are electrical components called crossover networks. Their job is to "split" the audio coming in so only treble goes to the tweeter, only bass goes to the woofer, so each driver is playing the appropriate sounds. When this is not done, it can cause distortion or even damage to the speaker. This can also be done digitally, which most AV recievers including yours does. It takes the low bass out from your surround speakers, and instead sends it to the subwoofer.
What I suggest is you do the same kind of digital crossover on your PC. Use each of your Onkyo speakers near subwoofer or bass module. Take the low bass away from the left speaker, and send it to the left subwoofer. And do the same for the right speaker and subwoofer. Believe me, it will make a huge difference. With bass modules, your Onkyo speakers' mid drivers will be relieved of the distortion from trying to play bass frequencies, and can just play in the frequency range where they have clarity. And the bass modules can give you much better bass than most bookshelf speakers.
The picture I showed you earlier involves mixing the center channel audio into the left and right speakers. This allows us to use that amplifier for one of the bass modules instead. After that, it splits the audio into bass and treble around the frequency of 250 hz, which I guesstimate will give you good clarity from both the Onkyos and most subwoofer drivers.
With this setup you have one passive bass module and one active using the amp from the JBL or some other amp. This is because the Onkyo has 5 amps and 1 preout for the subwoofer, and you want to have two amps left over for the surround speakers.
Now, for getting the bass modules. One option is to just buy another small subwoofer or two. You can get some very cost-effectively on fb marketplace or perhaps ebay. The small jbl sub you have now is not really much of a a home theater subwoofer, but it's designed to be more of a shared bass module for small sattelite speakers like what you have. Having this be separate from the sattelite speakers is a problem because all the bass, even deep male voices, basically sounds like it's coming from the subwoofer which is off to the side or under the desk or something. However, if these very close to the main speakers, they serve their purpose well. It's even better to have two in stereo, so that's what I think you should do.
You can try this in mono right now without buying anything, as long as you have a 3.5mm to rca cable. Just put the jbl on your desk, put the left onkyo speaker on top of it. Connect your 3.5 to rca cable to the multichannel input on the reciever, with the left rca going to the left speaker rca, and the right rca going to the subwoofer. If there is a low pass on the subwoofer, turn it all the way up or disable it if you can. Now using EqualizerAPO, mix the left and right channels together into both the left speaker and the subwoofer, and apply the low pass and high pass filters as shown in this picture. At this point, the onkyo and the jbl should be acting as a single mono speaker. Adjust the volume on the subwoofer until it sounds about right. Invert the polarity on the subwoofer, and use the setting which is louder around 250hz (check using onlinetonegenerator.com). Then you can also try adjusting the filter settings if you want. See if it makes an improvement you are satisfied with. You can also try adjusting other frequencies with peaking filters if some are too quiet and too loud.
If you buy, you want something about the right size so you can get your speakers to the same height, and have them be at about the height of your ears.
The harder but better way is to build two, better quality bass modules.
You could buy two perfectly cromulent 12"s for 45 bucks right now on parts express. Or four 8"s. Figure 55 bucks for mdf, glue, screws etc. If you can build a couple 2 cubic foot boxes for them, even 1 cubic foot + some dsp filters, you could turn what you have into a PC stereo system much better than the Edifiers for $100. Then just plonk the Onkyo speakers on top of them, or if you want to get fancy, build them into the box. You might spend a few bucks more on 3.5mm to rca cables, speaker wire, terminal cups etc but the total cost should be less than $150, cheaper and better than buying Edifier. Hell, they might even be better than the Rockits in terms of bass - the drivers may be cheap but a crappy 12" is probably still a match for a pretty good 8"
GRS 12PF-8 12" Paper Cone Foam Surround WooferGRS 12PF-8 12" poly-laminated paper cone woofers are perfect for use in sealed-box home theater and music systems. Thanks to their carefully optimized parameters, GRS 12PF-8 12" poly-laminated paper cone woofers offer a high degree of compatibility...
www.parts-express.com
or
CES VW-8820D 8" DVC Woofer 8+8 OhmThe CES VW-8820D 8" DVC Woofer is a robust, long-throw woofer that can be used in countless applications. A treated paper cone, thick, convex dust cap and foam surround combine to produce a stiff and light weight diaphragm. A large ferrite motor and sturdy 1.5"...
www.parts-express.com
I would build the bass speakers to be 2 feet tall, 1 foot wide, 1 foot deep. You could build the Onkyo mid and tweeter into the cabinet with their own compartment, or if you are lazy, just mount it to the cabinet with a screw. that is easy since it was meant to be wall mounted. And put the woofer below where the Onkyo speaker is. That would satisfy the recommended volume for the 12" driver while making use of the vertical space above your desk, and having the weeter about ear height. If 12" is too wide, you could make a narrower version with two of the 8"s.
I really enjoy improving speakers by making better cabinets for them out of salvaged plywood and mdf I get for free from curbside furniture. Not only can you get pretty good speakers for extremely cheap, you can also learn something each time and have something you can be proud of that you made.
If you get a few hundred bucks more in the future, I would recommend a umik-1 and then home theater subwoofer. The mic will give you much more information for calibrating your system and the subwoofer can extend your bass further into the lower octaves. And with the information from the mic and the knowledge you gained already, you would be more able to set up the subwoofer very well.
I realize that is a lot, but it comes down to spending time or spending money. So good luck with whatever you choose.
