External DAC for iPhone connection to stock stereo makes a HUGE difference

I posted this discovery in another thread this week, but after having listened to it for a few more days I've decided this is a substantial enough improvement that it deserves its own thread.

I've long been unhappy with the sound of my stock stereo ('13 PiP base which has NAV but not JBL). My primary source is my iPhone 5S connected either through bluetooth or USB. Unlike some other cars I've had, I don't find much of a difference in sound between the two provided connections. My complaint is a bit different than some of those that I hear here - I actually find the low-end passable in this car - I prefer a balanced and clear sound to booming bass. My biggest complaint was that the stock system sounds harsh (as in digital artifacts) and rather un-focused - everything seems to be smeared together making it difficult to discern individual instruments or notes. Turning it louder just makes things worse, and actually makes my ears hurt.

So last week when I received an HRT iStreamer to use in another car, it was trivial to hook it up in the Prius and see what it did for the sound. I was frankly floored. The iStreamer is an external DAC for Apple iOS devices. It retrieves the digital signal directly from the device unaltered, performs the DA conversion internally, and outputs to a pair of RCA jacks. It has a separate 5v usb connection and includes a mini-usb to 9v adapter to power it. It also charges the device when connected (including an iPad) and pauses the music automatically when you shut the car off.



The Gen III Prius is a perfect candidate for this device because all the connections you need are right in the bottom of the center console. Connection takes about 30 seconds and you are left with your Apple cable alone coming out of the console. Surprisingly, this little device fixes a tremendous number of the issues I have with the stock system. Instruments occupy something resembling separate spaces. The bass becomes tauter and punchier. The digital graininess is gone. It makes the system produce a sound enough like music that I actually want to crank the volume.

As I'd purchased the iStreamer for another use, at the moment I have an alternative solution at work in the Prius composed of other audio parts I already had. iOS7 unlocked the digital output stream to anyone using the lightning to usb camera adapter. Connecting that cable to my Fiio E7 DAC/headphone amp, and the output of the amp to the Prius' aux-in produces the same improvement (although without the convenience of permanent power for the DAC or charging of the iPhone. The battery life for both devices is so long however that for now, this is good enough. The Fiio is rated at 80 hours so I should rarely have to charge it).

Obviously you lose the album artwork and ability to skip tracks, etc from the factory radio, but frankly that's a small concession for this improvement. As my car is a lease, this is an especially nice upgrade - I may still do the front speakers - but we'll see - at least this discovery makes the system enjoyable. I would encourage anyone who uses the bluetooth or USB connection on their stock radio and is unhappy with the sound to consider one of these devices before pursuing larger fixes. It's well worthwhile.