When you resume playback after the buds have been in their charging case, the sound continues from where you left off. So, if you load up the earphones with a dozen hours of music, you’ll just gradually work your way through it. When they get to the end of the contents, they just go back to the start and begin again.

 Books and podcasts

You can take advantage of this to load up the earbuds with an audiobook or podcasts if you’re comfortable locating their files on your phone or computer so you can copy them to the Sony WF-SP900 earphones. Whatever you’re planning to listen to, take a few moments to consider their order. If you like listening to albums in track order, then make sure the file names have track numbers at the start.

Sony WF-SP900
Fast enough file transfer, although it weirdly steps down in speed towards the end.

To check load speed, I grabbed 500+ MP3 tracks amounting to a touch over 2GB and dragged them to the Sony WF-SP900 earphones (in their charge case). Windows initially reported a copy speed of a bit over 6Mbps, but about three quarters of the way through the speed stepped down to around half that. Altogether, it took six minutes and thirty seconds for the transfer. Not superfast, but not so slow as to make one reluctant to replace the music from time to time.


I was not an enthusiast for the sound of the Sony WF-SP900 earphones in their natural state. They were a bit tinny, with a distant bass. I found them fine for podcasts, with good clear voices, easy to understand. But music? Not so good.

But, happily, the Sony Headphone app on my phone came to the rescue. It has EQ functions plus something called Clear Bass. There are only five EQ sliders, with the deepest one centred on a relatively high 400 hertz, which isn’t really bass at all. But I found by putting that one at the maximum setting, pulling down the three middle sliders a little, and setting Clear Bass to the maximum (it’s sounds like it’s a bass boost control), the Sony WF-SP900 earphones were able to deliver listenable, enjoyable music.

The deep bass was still quite recessed. But for the first time I heard the bass drone (in the distance) of one of the tracks provided on the earphones. I copied the track to my computer for a listen on my own well-balanced system, and that bass line was much louder. Still, the deeper notes (which were at 41 hertz) were now audible through the earphones, instead of being not previously noticing their existence.

Sony WF-SP900
For music, I liked the sound best with these EQ/Clear Bass settings


For out-and-about wear, the music sound was good. But you can expect a reduced battery life with the bass being turned up so high.

All that was with the land-based earbud tips. The ones suitable for in-water use were a different matter. They quietened the sound by a marked degree – I’d guess it at 6dB, perhaps more. They also killed the treble.

Within the Headphone app you can set up a Quick Sound Settings function. This gathers Ambient Sound Control and EQ under the one setting, and this can be switched on and off using one of the earphone control buttons. I found that having a flat EQ when using the swimming tips helped clarity and gave a so-so sound. It was okay for voice. I’d be inclined to do my swimming with podcasts, rather than music. With the swim tips in place, there wasn’t really a setting that didn’t have at least something of the feel of listening via two tin cans connected by string.


With the Sony WF-SP900 earphones, swimmers now have a means of occupying their minds while they’re pounding out the laps in the pool. All I can say is, well done.

Sony’s website for the Sony WF-SP900 earphones is here.

Sony WF-SP900 Wireless Sports Earphones (review)
Name: WF-SP900 Wireless Sports Earphones Price (RRP): $499.95 Manufacturer: Sony
Hey, they work in water! Good sound when EQed using app Secure fitUSB C conneciton
Fairly expensive
Value for money
Ease of use
4.6Overall Score