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BT355 HD Radio Line Leveler And Pre-Amp Adapter for 2014 and Up

1.00 LBS


Product Info

No More Flash Headaches!

Our new BT355 Line Leveler allows you to install an aftermarket amp and speaker system on your 2014 and up HD without flashing the radio.

Included in our 2014+ amp packages.


  • Removes bass distortion when connecting an amp to the factory 2014+ radio
  • High quality three stage circuit for optimal sound quality and precise filtering
  • Adjustable level and frequency
  • Adapts high (speaker) level inputs to pre-amp outputs


  • For 2014 and up stock HD radio*

*NOTE - Ultra models do not have a rear speaker connector in the fairing. For plugging in rear speakers, please see the Breakout Connector for Ultras.


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Product Reviews

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Showing reviews 1-4 of 13 | Next

  1. Overcoming Harley 5 Star Review

    Posted by on 4th Mar 2018

    I did not want to be stuck with Harley’s stage 2 stuff but was going to. Then I found out Biketronics has developed these line levelers. I installed a different audio system for reasons untold. These units installed as per their instructions results in trouble free audio. I did not have to go to Harley for anything. On a side note. The people & products at Biketronics are extremely awesome. Call them up if you’re looking at upgrading. I promise you they will do their absolute best to fix you up.

  2. Just what the sound doctor needed 5 Star Review

    Posted by on 27th Feb 2018

    Customer service is A1. Product shipped fast and arrived as described with great instructions. Will definitely recommend to anyone wanting great sound with the factory boom audio unit

  3. Clean/easy to adjust 5 Star Review

    Posted by on 12th Jan 2018

    Worked as advertised. Very clean sound by eliminating unwanted frequencies. Had to tweak HPF just slightly to achieve ultimate settings with Fosgate AMP. Then you can boost gains on AMP to get ultimate volume. Must have for Fosgate system to crank to FULL volume. Very impressive after that.

  4. Forget The Flash! 5 Star Review

    Posted by on 5th Jan 2018

    Taking my bike to Harley to get them to flash the the stock head unit to flatten out the audio proved to be a pain. I was literally paying them to do something they could not figure out how to do. Save yourself time and headaches by doing this yourself with these line levelers. After installing a complete Rockford Fosgate kit in my 2018 SGS, I added these line levelers and now my audio is loud, bright and clear with zero distortion; it actually hurts my ears if I crank it all the way up and I have a stage 1 done with a Python exhaust. If that's not loud enough for you - get your hearing checked. I did have to make some adjustments a few times to get the gain set perfectly as I am sure you will need to as well, but this is something that is done easily, by yourself and without having to pay a shop to do it. The only thing you need to do at Harley after completing this is to tell them to turn on all four speakers so you can have true fade functions. Technically you don't NEED to do this, but if you have OCD like me, then you want everything done right. Bottom line is this; if you are adding after market amps and speakers - through these line levelers on and your upgrade is compete!

Showing reviews 1-4 of 13 | Next

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