I'll take a stab at this.
I'm reading a lot "between the lines", here and my impression is that no matter what kind of speakers you roll into the system, you're not completely satisfied with the presentation. Hence, you're looking to upgrade your system and are looking for some different components on a budget. Your post is intended to inform yourself of what others are using and if there are any pieces that sell for lower prices that are of good quality. Am I getting close, here?
You have some adequate speakers in your line-up and I don't believe either the JBL100's or the DQ-10's would dissapoint you if you had everything else optimized.
One piece of information that would be critical is the size and configuration of your listening area. Describe it in a few words.
Also, if you're listening to the Marantz in FM and haven't had that receiver serviced and the FM section aligned, you won't be getting very good results. I've owned them and my experience mirrors others that the FM sections need service after a lot of years.
Why are you using an EQ? Is it because you have one or are you trying to boost some frequencies that you percieve are missing? I would remove it from the signal chain. My initial impression is that it is not needed and might be degrading the sound.
As simple as it sounds, are your cabling and wiring pieces adequate for the job? Sometimes a wire switch will bring good results.
Reading further between the lines, your statement about "clarity" and "horns" seems to suggest that the sound you're hearing is not up to your expectaions. Maybe the sound is somewhat diffuse or "muddy"? Some of that might be the choice of receiver. Marantz is noted for it's laid back "three martini" sound and if you're looking for a bright, crystalline presentaion, a better choice is out there. A real low budget experiment would be to buy a Sonic T-amp or similar chip-based amp to see what the difference in amplification designs can do for you in place of the Marantz.
To get the most out of your speakers, I would start with the JBL's. Your listening habits probably is in gear with that pair more than the others. Inspect them and listen closely (your ear against the drivers) to make sure they are operating with reasonable function. I've owned the 100's and a few of the JBL Studio Monitors. Clarity won't be an issue, necesarily, but the real forward presentaion of the midrange, coupled with the booming bass might not sound that good. To remedy the overpowering bass, you can try stuffing the port with straws, socks, fiberfill, plumber's plug, or anything else you have handy. Do a little reading on how others have tried to tone down the boom. The midrange is another matter and I didn't find it totally objectionable. A cross over modification or even just using the mechanical controls might be enough to get that settled down to your listening pleasure.
For your purposes, I would think about optimizing what you have, first, add or subtract one piece at a time, and don't "throw out the baby with the bath water", so to speak. Room placement and listening area tweaks can bring good results, also. I think you can reach some better levels with what you have.
If the "baby" does have to go, here are a couple of recommendations: system synergy, if you are keeping the Marantz, try some speakers that are brighter. The Axioms were mentioned, previously, and would fit the bill. The tweeter and smaller woofer two-way do add a lot of clarity. They fit many common room sizes.
Try out some different amplification. A good dual power supply integrated amp and separate tuner is definitely a step up, IMO. I'm partial to Kenwoods and Sansui but that is just me. Maybe you could borrow an amp from someone local and plug it into your system?
That's about all I have from reading between the lines. Good luck on your journey.
