I'm obsessed with a music streaming service millions of people probably don't know they can use for free

I held onto my 2008 little yellow iPod for an impressively long time before it finally kicked the bucket late last year.

It only took a few music-less commutes through the subways of New York City before realizing that I needed a replacement source of tunes.

Unfortunately, I couldn't just load songs from my iTunes onto my iPhone because of a weird software incompatibility, so I started trying to decide between the wide selection of music streaming services out there today.

Spotify? Pandora? Google Play Music? Rdio?

Because I wanted to get my music fix underground, I figured that I would have to shell out for a premium version of a service so that I could download songs to my phone for offline listening.

In the end, I became obsessed with a service that millions of people probably don't know they can use for free: Amazon Prime Music.

As an ecommerce reporter, I've known about Amazon's streaming service since it first launched last summer. It's only available to people who pay $99 a year for Prime, the membership program that most people join because of the 2-day free shipping it offers on a ton of products. Although Amazon refuses to lock down an exact number of Prime subscribers, it says there are "tens of millions" in the US alone.

I had downloaded Amazon Music initially for research purposes, but forgot about it soon after (those were the iPod days, remember?).

While stranded in a music desert, though, I decided to give it another try before dropping $10 a month on Spotify Premium.

After all, it was free, since I already pay for Prime for its speedy shipping.

I quickly fell in love for a few reasons:

• Amazon lets me download all the music I want onto my phone, so I can listen underground or without using my cellular data while I'm walking around
• I can download a bunch of music for free, but the player also pulls in any music that I've ever digitally purchased from Amazon (for me, that's about four albums)
• The selection is comparatively small - Prime Music has "more than one million songs" versus the over 30 million on Spotify - but I was quickly able to put together a playlist of more than 450 songs from artists that I love. That number has continued to grow as Amazon adds new music or I discover new bands through its playlists features.
• That's another thing that I like about Prime: You can browse a bunch of playlists curated through a combination of Amazon's algorithms and a human editorial team (my personal favorite is Coffee Shop folk)

Amazon Prime Music definitely won't be a good fit for everyone. Besides a much, much smaller selection overall, the service doesn't have as much rap and EDM available as other services. And you shouldn't expect to see the latest albums as soon as they drop (for free at least, you could buy the album on Amazon proper and have it show up in the streaming player).

But because I love indie rock bands and folk music and generally don't care about getting new albums (in part because several of the bands I'm in love with haven't released new music in years), I'm constantly using the app and am absolutely a huge, unabashed fan.

I'm not saying that people should ditch their Spotify, Rdio, or Pandora subscriptions if they're already all signed up and digging it. But if, like me, you're one of the tens of millions of people who already pay for Amazon Prime and you aren't an evangelist for any other service, give it a try.

Because the key is that if you already pay for Prime anyway, it's free.

Here are some of the playlists Amazon Prime Music offers:

Here's what the player looks like when you're offline streaming:

Amazon

Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.