We tested the HBH-DS970 with the Sony Ericsson K790a Cyber-shot. We had no trouble pairing the devices and were ready to go in no time. Calls came through loud and clear, and callers said they had little trouble hearing or understanding us. In noisier environments, audio quality faded just a bit but the headset's automatic volume adjustment worked rather well to combat any changes. The HBH-DS970 also features adaptive frequency hopping for minimizing interference and digital audio processing (compression and noise cancellation).
Our only real complaint is that because the microphone rests just below the right earpiece, the HBH-DS970 can pick up a fair amount of wind noise. Callers asked us to repeat ourselves on a few occasions, but it wasn't enough to distract from the headset's excellent performance overall. Calling features were plentiful with voice dialing, call transfer, call reject, redial, and muting among the offerings. And as with all Bluetooth devices, the standard range is about 30 feet, and the HBH-DS970 can be added to up to 10 devices.
Music quality was admirable as well, and we liked that we could activate the K790's player just by pressing the HBH-DS970's play/pause button. What's more, we loved being able to change tracks and adjust the volume without touching the phone. There's a bit of a lag when making a command on the headset, but it wasn't bothersome in the least.
If your phone doesn't have a digital music player you can connect to another music device, but the user experience isn't quite seamless. Though we were able to connect to our Sony Ericsson W600i (for calls) and our K790a (for music), we had to pair each device separately and then switch to multi-device mode for a simultaneous connection. Moreover, though music stopped automatically when we got a call, we had to start it again after the call was over. And even then, it didn't pick up to the same place that we had left. It's also worth noting that since the headset's music player button connects only to the most recently paired device, you'll have to pair your devices in the correct order.
The Sony Ericsson HBH-DS970 has a rated battery life of 6 hours talk time of and 12.5 days standby time.