I tried the two lines with definitely unique music, for example, metal, electronic, dubstep, and vocal concentrated (Christina Perri. In the entirety of my testing I found that despite the fact that Reference sounds better then the majority of alternate brands, that Kappa sounded better then the Reference. great bass The bass was significantly more greater and exact, and the highs and mids were much clearer(And yes I played around with the tweeter control on the speaker for the two speakers). On the off chance that you ever find the opportunity to think about these, you'll see on the off chance that you tune in to the Kappa for somewhat then switch, the Reference sound sloppy in correlation. I should include that with a legitimate intensifier the Kappa hit as hard as a couple of good 10" subs. However, regardless of whether you abandon an amp with these children despite everything they sound truly damn great on all levels it just takes all the more tweaking from your head unit. In any case, ensure you utilize one of the new pioneer heads to do it, similar to the Pioneer DEH-X8500BH (That's the one I'm moving with). I couldn't duplicate even nearly as great of lows, mids, highs, or sound lucidity utilizing some other name mark. You can even return one age for the Pioneers with the MIXTRAX highlight, those that I tried appeared to give me a similar nature of sound. In case you're thinking about whether you ought to get an amp.. For me I was hoping to get speakers that would give me enough great clean bass with the goal that I wouldn't need to introduce subs. That said I will buy an amp to run with my setup, in light of the fact that in my testing when I included an amp, these folks truly woke up, if sound quality with an amp is 10/10 I would state that without an amp I would rate them at around a 6/10. The nature of sound appeared to be the same with some tweaking in the E.Q. on the Pioneer head yet they got strangely noisy (without trading off sound quality) when I included an amp in with the general mish-mash. awesome quality