This is really a no frills FM-Bluetooth Transmitter. But there are some faults to this. Let me share the bad then move on to the good. But let me share this major tip. Set the transmitter volume to maximum.While this is a FM-Bluetooth transmitter what is really meant for phones. This product isn't it's strongest feature. Why? Let me explain. When making or receiving a call. You have to press your preset radio station if it's not already chosen to make or receive calls. Especially if you are listening to another preset radio station. It can be annoying to hit that FM Transmitter station. This has happened to me on several occasions. But it'll be repetitive soon.Now several users has mentioned about the feedback noise. While this is true and it stems from the alternator. It's only when you are on a call and the radio volume is on a very high setting and this does not affect during bluetooth music streaming or using the USB Drive. What I mean is that, when you need to hear someone from the other end. The transmitter isn't as strong to produce the sound to all speakers. Even when you have your phone bluetooth volume on maximum. This issue is whether you have the window up, down, AC on or just simply road noise entering in the car's cabin. But again this also depends on your own car speakers as well. So that is one feature that could be improved if the manufacture decides to do so.My other annoyance, is the USB connection. Depending on the cable or USB drive you use. It can be somewhat a tight fit as you can see in my pic. Sure I can buy a right angle cord to charge my phone. But why add more cables to my collection?Now for the USB drive. This can be somewhat a good thing and a bad thing. Upon start up. It can either be recognized or not. Sometimes while playing it'll just go to "unrecognized" for several seconds. Then it comes back again. This product only plays MP3's. No wav, mp4. I cannot comment on AAC or ALAC as I don't have songs in those format. So if you going to bring your music onto a USB Drive. Be sure it's in a format that the KM 30 can play. I haven't tried the SD card feature as of yet. So I will make an update at a later time. But I'm sure it'll be the same.The good.The Bluetooth streaming is great. Providing you set your equalizer on your phone correctly. Most modern Smartphones has this feature. So I suggest you play your favorite song or a song that has a balance of bass, treble and mids. This will ensure that whatever streaming music you use. You will get that sound great. Even with the OEM speakers. Once that is complete. You will want to adjust your stock your radio sound settings. Most stock radio has bass, mids and treble. Set those at neutral and adjust accordingly. Then move onto the KM30 bass and treble and adjust accordingly. This will take some to get the sound you are after from your .Using a USB Drive? Well this all depends on your music library. If you have a library of music on a hard drive, not all music are set a particular bit rate (kbps). I know I don't. I have bit rates ranging from 92kbps to 320kbps. So the best method from my 2 week experience. Again find a music that is really balanced with bass, mids and treble and have a 128kbps. I actually used Metallica- Hollier than Thou and Delinquent Habits - California. Yes I have a wide range of music taste when I cruise. When you play you will have to make adjustments to the bass, mids and treble from your stock radio and from the KM30.So music lovers between normal radio stations, music streaming to music on a USB drive. You will need to find that balance of sound. While this might be a pain. It's so much better than making a phone call.Again this is a no frills FM-Bluetooth Transmitter. This works perfect for older cars once the sound is dialed in correctly.My only suggestion that this product would have an edge over the others. If this could pivot left and right. But that is a small pet peeve on my part.Enjoy!Car2004 Mazda3 Hatchback.Stock Radio with 2 year old JBL Club 6x8 Speakers in 4 doors. No amps.