Merkin

symphony HU looks so nice inside but the sound is terrible. all the frequencies are rough and boomy. boston acoustic sub, kappa perfect speakers and MTX amp shouldn't sound boomy at all.

maybe it's time to get an AVIC D3

diagnosticator1

improve the system dynamics for use with the amp/s and drivers you are using now.

Merkin

stock HU just sounds dirty and lacks the ability to shift eq curves to have any significant improvement.

also no internal crossover and filters to clean it up.

stock speaker woofer/tweeter doesn't even get filtered, no crossover in the entire stock system. add on EQ would help but at that price point and effort it would be economical to get a better HU.

any signal out cannot be filtered for a specific frequency range so my amp and speakers have to just play muddy signals.

DirkM

If not, make sure that the head unit is coded for Bose. Otherwise its internal EQ tries to make the cheap factory speaker sound good - which results in poor sounds when you replace the speakers. The Bose coding gives you an un-equalized line out which should sound much better.

Merkin

not coded for bose

DirkM

That's the reason.

diagnosticator1

Well, for what it's worth, see my new post on the Sym II + HU install to follow..

diagnosticator1

<ul><li><a href="https://forums.audiworld.com/audio/msgs/58227.phtml">Here.</a></li></ul>