I bought the cd-mc20 from sonic and upon receiving it i found out that i could not get it to calibrate to my 4300dvd because of the relay i'm using to be able to watch video while driving. At this point i'm not sure if it will do the job that it was designed to do or not.

(Note: Sonic Electronix does not endorse any attempts to bypass the safety features of the stereo. However, we have chosen to include this review as it contains useful information for those who choose to make this fairly common modification.)

I own this product and it do his job very well .I recommend to everybody
for good sound setting in the car.

Worked very well on my Pioneer 4300 DVD - In regards to not working with the bypass: This is correct. However it's a super easy fix. You need to supply power to the BLUE wire going into the relay from the headunit. What I did was splice a wire from that blue wire, into a 12 volt ACC power wire elsewhere under the dash, and for fun attached a simple switch that I had kicking around. Now all you need to do is flick the switch and boom - the bypass is 'bypassed' and the HU works correctly allowing you to run the auto EQ.

Not sure if it was my ears or the mic, but the calibrated sound was terrible. Much better setting the HU by hand. Seemed like it boosted the middle frequencies too much.

Works as stated. If you don't want to spend a lot of time to get stereo tuned, this is the way to go.