Features

Equalizer: Each of the line outputs (front, rear, and subwoofer) has its own graphic equalizer. In each band, both channels (left and right) can be adjusted simultaneously or individually. Each line output also has two programmable parametric EQ bands with adjustable width (1/12, 1/6, 1/3, 1/2, 1, 2, or 3 octave). The adjustment range is +/-12 dB in 1 dB increments.

Front: The front graphic EQ has 30 bands from 25 Hz to 20 kHz in 1/3 octave steps. There are 59 bands from 25 Hz to 20 kHz for the two parametric EQ bands.
Rear: The rear graphic EQ has 19 bands from 31.5 Hz to 16 kHz in 1/2 octave steps. There are 59 bands from 25 Hz to 20 kHz for the two parametric EQ bands.
Subwoofer: The subwoofer graphic EQ has 14 bands from 25 Hz to 500 Hz in 1/3 octave steps. There are 33 bands from 25 Hz to 1 kHz for the two parametric EQ bands.

User Memory: There are eight memory presets to save equalizer curves, four for the main inputs and four for the auxiliary input. The memory is non-volatile, so it isn't lost if the battery is disconnected or runs dead.

Crossover: Crossover points for the front, rear, and subwoofer outputs are set independently. The front and rear high-pass crossovers offer 108 frequency options from 15 Hz to 8 kHz; the low-pass sub crossover offers 54 frequency options from 48 Hz to 1 kHz. The slope of all three crossovers is 24 dB/octave.

Subsonic Filter: The subsonic filter crossover point is adjustable; there are 24 frequency options from 15 Hz to 56 Hz. The crossover slope is 24 dB/octave.

Speaker Input: The speaker level inputs are compatible with nearly any factory stereo system, even most Bose systems. There are 4 pair of inputs that will accommodate up to 400 watts.

Channel Summing: The DQL-8 has the ability to sum together multiple input channels (4, 6, or 8) from the factory source unit into 2 channels. This is handy when the factory system has multiple, actively crossed-over signals sent from the source unit or amplifier(s). For example, in some vehicles there is an actively crossed-over tweeter, midrange, and woofer all in the front of the vehicle. The DQL-8 lets you take all of those signals and sum them together to get a high-quality, full-range, pre-amp signal without the use of any additional cables or hardware.

AutoMode Inputs: When there is no signal present at the channel 4 input, the channel 3 input automatically feeds the channel 3 and channel 4 outputs.

Auxiliary Input: There is a pair of RCA auxiliary input jacks on the unit so you can easily add an iPod, satellite radio, or other secondary source. The aux input is engaged by pressing the knob on the wired remote.

Balanced Input: Using the balanced differential input circuit on the auxiliary input cancels noise picked up in the transmission line between the DQL-8 and the source unit. The input can be set to balanced or unbalanced if needed.

Input Gain: The input gains for the 4 pair of speaker inputs and the auxiliary input are set independently. You can boost or cut the signal to match the source output to the DQL-8 input.

Output Level: The adjustable output levels allow you to increase the head unit's line voltage to the top of your amp's input range; up to 7.5 volts RMS. The output level is adjusted independently for each of the 3 pair of line outputs.

Auto Turn-on: The main speaker level input has a signal sensing circuit; the unit turns on when there's a speaker level input signal and turns off when the signal disappears.

Remote Output: The +12 volt DC remote output will trigger an amp to turn on whenever the DQL-8 is on. The remote's maximum current output is 1 amp.

Remote: The included wired remote controls either the subwoofer output level or the master volume of the entire system; which one is selected in the menu. The remote is designed to be dash mounted, within reach of the driver; it can be mounted under the dash with the supplied bracket, or the bracket can be removed and the knob and LED can be custom mounted through the dash. Pressing the knob engages the auxiliary input.

DDC Input: A wired Digital Dash Control (item number 161DDC) can be added to the DQL-8, giving you remote control of all the menu functions.

Ground Isolation: The power supply ground is switchable, in case of ground loop noise. The factory position is fully isolated (typically the best choice), but can be changed to Ground or 200Ω.

Terminal Blocks: The power/ground/remote in/remote out terminal and the speaker level input terminals are removable; the wiring is attached to the terminal block, then the block is plugged into the DQL-8. The terminal blocks will accommodate wire up to 12 gauge.

Specifications:
Maximum Speaker Level Input: 400 watts @ 4Ω
Maximum Output Voltage: 7.5 volts RMS
Frequency response: 10Hz-22kHz
THD: 0.01%
S/N Ratio: 105 dB
Balanced Input (aux) Noise Rejection: 60 dB
Input Impedance: 20 kΩ
Output Impedance: 150 Ω
Crossover Slope: 24 dB/octave
Subsonic Filter Slope: 24 dB/octave

The equalization capabilities of this unit are probably the most advanced I have ever had the pleasure to use, and that includes the company of some pretty esoteric pieces used in the professional sound industry.

The power of this EQ as a tuning tool is compounded by the fact that you have the ability to tune each channel individually or as stereo pairs. You also can select the "Q" or bandwidth of the EQ filtering, from as fine as 1/12 of an octave to as wide as three octaves! You could choose to use the parametric EQ to make overall adjustments, and then use the main EQ to make individual channel adjustments that will then be overlaid on the previous settings. With the EQ, and the two parametric EQs, it's possible to make large corrections, and then make fine tuning adjustments even within those large corrections. Read that again. Think of it as having three separate and slightly different EQs connected in series, where you can adjust boost and cut, frequency, and filter Q and the end result is the cumulative response of your adjustments on all three. The DQL-8 allows you to not only EQ the system, but it allows you to make almost infinite adjustments on top of your previous adjustments! My son put it like this: "You can EQ the EQ that you've already EQ'd!" Have a look at the graphs for an example. There was a time when most of us thought a 1/3 octave EQ for each channel was plenty, but after you use this thing once, you'll be spoiled for life.