I have never owned an in-dash EQ before, but I am an Audio Engineer by profession, so I know a fair amount about audio. I bought this unit to give me greater control over my 4-channel amp and my monoblock sub amp. This unit is hands-down much better than your average head-unit's EQ. I love the crossover freq knob for the sub channel. This is crucial and I will never live without one again. Having the subwoofer volume and fader right at my fingertips is also tremendous. The unit seems well-built, and I am getting LOTS of clean signal with this EQ. Just some slight hiss when all is quiet. You can even cut back on the high freq knob to get rid of most of the hiss if needed, but it is VERY minor.
On to the flaw of this unit:
The 4-band EQ is heavily congested in the lower-mid spectrum, and only gives you one band for high frequencies. That normally wouldn't be so bad, but the top band is 20KHZ which is at the VERY top end of what you can hear. Pair that with the fact that the "mid" band is set at 1khz (too low) and you have a HUUUGE gap in the frequency band that you can do nothing about. I ended up using the mid and high bands from my head unit to give me more control. I find it hilarious that 2 of my 3 bands in my in-dash fit in the hole this unit left. I will try to show how much of a gap this unit has:
Hopefully this will visually show you what I am describing.
Having said all that, I am still extremely happy with this unit. It has boosted the signal, given me greater control, and it even looks very nice. I would recommend this unit to anyone on a budget who really gets into the hobby and wants more stuff to play with, and better sound.