Hi Dave,
Welcome to the forum. Nice find on the plasma @ Wallyworld. Whereabouts are you? Btw, it is best to forget what you know about car audio and start fresh without any preconceived notions.
Anyways, a couple questions. I first saw these speakers on demo at best buy, and they completely blew me away. But i cant seem to get mine to sound like that. I know that it will take time, but I have a couple questions about tweaking. Their sub was not even on, and their same speakers as mine were producing a good amount of bass. Now I know I need to tweak the receiver a bit more, but I am just learning it now. I need to find out how to adjust the bass for the fronts, center, and the subwoofer through my receiver. What are the benefits of bi amping and bi wiring, and do you need a 7.1 receiver to do bi-amping? I only have spots for two fronts on my receiver, so bi wiring is an option, but is it worth it. Also, what are some general tips. Sorry for being a nooby, but I really want to excel at this. Is there a way to amp the fronts solely..off a seperate amplifier that fits a budget? Thanks for all the help!
As mentioned, the default setting on your pioneers internal XO is 100hz. Look at pg 37-39 of the manual, where it explains how to adjust that setting. Either bypass (if possible) or set it to the lowest frequency (my quick look at the manual didn't show the actual frequency choices, but on my ancient VSX817, it was 200, 100, 80 and 50hz). You would want 50hz or lower to experiment. You can always reset it higher if/when you add a sub.
Keep in mind also that what you hear, especially at low frequency with your type speakers, is going to vary between your room and Best Buys, due to the speakers placement/interaction with the room.
The only benefit to "bi-wiring" is if you "bi-amp". It shouldn't be necessary in your scenario. Your speakers are efficient and the Pioneer has enough power to drive them loudly. Pioneer makes terrific (scientifically verified by folks like Dr Earl Geddes using low level linearity testing of his GedLee metrics) amp sections in their receivers.
If you wanted (again, probably no need) to connect a separate amp, you should have bought a model with pre-amp outputs.
Btw, if your equipment specifications are correct, you can attain >116db @ 1m continuous sound pressure and around 119db peaks (1m). Even with dissipation loss of 9db sitting 9' or so away, those are dangerous to your hearing levels. Again, forget the idiocy of car audio "SPL Drag", etc. >150db levels. You won't enjoy any music if you damage you hearing...or go deaf

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Fortunately those Klipsch require very little power to drive loud and the claimed 80w of the 520 should be plenty. Unfortunately the budget Pioneers really limit (or at least used to) where you set your crossovers. According to your manual things haven't changed much since the last one I set up and your only choices are "large or small" L&R front speakers and then a single crossover point for all of the "small" speakers. That really limits you. If you set them to large then everything intended for the mains goes to the mains even if they can't deal with frequencies below 40hz. Or you can set them to small and use the crossover to limit what is sent to the mains to the low limit of the most limited speaker that you attach - probably the center or surrounds. More advanced receivers like say the Onkyo TX-SR608 allow you to set a crossover point for the mains at say 40hz and then a separate crossover point for the center at whatever it likes, and still another for each pair of surrounds. If you're still within the return window I'd go with a more advanced receiver. If not then I'd set the mains to small and make sure that any other speakers that I attached are rated down to say 80hz and live with that as the crossover.
BTW, just looking at your manual it looks like the crossover on the 520 defaults to 100hz.
I've noticed that you recommend Onkyo just about every thread. You should make it your sig - "Buy an Onkyo"

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I generally don't take the time to comment on such sillyness, but it appears your continuing stated issues with Pioneer(s), etc vs Onkyo, is user-incompetence-blame-the-equipment related. My very old Pioneer has XO flexibility and it appears this new one does as well. It helps to be able to understand...not just read...the manual:
1 Select ‘X.OVER’ from the SP SETUP menu.
2 Use (Up/Down Arrow) to choose the frequency cutoff point.
cheers,
AJ