as bald waldo said, amplifiers with a high level input means they already have a "loc" built in.... it just reduces voltage down to a level that wont clip and distort the signal... basically a resistor of the right value..... you CAN overpower your stock speakers about 30%, but only if its a clean signal. typically, factory speakers are only good for about 22-25watts rms. thats the same power a head unit typically puts out.... because they are built that fragile, usually means they are built more sensitive, but not always the case... many aftermarket speakers will typically put out less for the same power, but the cones are also not built for much more than the low power, so its kind of like firing 5.56 rounds out of a 22lr barrel..... if you have access to a meter, you can use a 4channel amp, from a boost box to a big 4channel and set the max voltage to the speakers by calculating what voltage it takes to reach your desired wattage rms, which can be what the speakers are rated for plus 30% and it might last for decades that way, or minutes. theres some amps that can handle 10.5v inputs, and many factory systems that send 9-10vac to the speakers. if you find those matching up, then you can wire the speaker outputs straight to a pair of rca wires to the amp "low level" inputs and turn the gain way down to match. i havent messed with the brand new yotas, but they have, in the past, been in that 9.5-10.5 range, so it mostly depends on what amp you choose. either it can take the 10.5 or less, or it cant, but has high level inputs. unless you buy an amp that doesn't meet the criteria, then you shouldnt expect to spend more than 30 for a loc, unless you fond one thats a dsp that does more than function as a pair of resistors/pots that lower the speaker level voltage.