This and That:
Nice unboxing experience.
Comes with two sets of high quality RCA cables (RCA to RCA as well as RCA to 3.5 mm TRS) (their plugs fit quite tightly though and are difficult to remove), a power supply with several adapters, and last but not least a small antenna.
Sleek design and high build quality. I really like it.
Rather small in size - flatter than my PC mouse and not as long as my Apple iPhone 4.
Shell milled from an entire block of aluminium.
Looks somewhat like a small Apple Mac Mini.
On/off button located at the back. Somewhat soft but well defined accentuation point.
Small LED indicator at the top (that's perhaps a bit too bright for my taste).
Automatic stand-by after 30 minutes without activity. Can be disabled by holding the power button for 10 seconds (re-activated by disconnecting power).
Holding the power button for 5 seconds, one can hear a relay clicking, along with the white LED turning orange, which indicates that the RCA outputs don't output an analogue signal anymore but a digital one and act as SPDIF Coax outputs to connect an external DAC.
Repeating this switches the output back to analogue stereo.
Bluetooth volume control possible with my iPhone 4 but wasn't with my BlackBerry Q10.
Easy and super convenient Bluetooth connection that doesn't require pairing.
Very good connection stability and range.
aptX supported.
Sound:
Frequency Response:
Nicely flat, just as it should be.
The other measured values look good, too (very good dynamic range and noise performance, good total harmonic distortion and crosstalk, somewhat high intermodulation distortion).
Perceived Audio Quality:
In the past, with several Bluetooth receivers, I could reliably tell a sound quality difference compared to a wired transmission. Not so with the Relay - having used my BlackBerry that transmits aptX Bluetooth, even when the Bluetooth DAC was connected to a high quality headphone amplifier such as my Leckerton UHA-6S.MKII and when I was using sensitive, resolving multi-BA in-ears such as my Shure SE846, it sounded just as transparent as a wired audio setup. No noise or any other artefacts. The transparency is absolutely on the same level as when compared to a wired audio chain. With my iPhone 4, I imagined that there's perhaps a very subtle difference in treble precision compared to a wired chain, but I couldn't reliably reproduce that. And as mentioned, in my controlled and volume-matched test, the Relay's transparency and sound, when used with my BlackBerry Q10 that transmits aptX, was just as high and clean as when compared to a wired audio chain.
Sounds subjectively just as neutral and transparent as any well-designed modern device should.
Conclusion:
High build quality, easy to set up and use. Sound quality subjectively just as transparent and clean as from a wired device (I couldn't detect any audible difference in a volume-matched direct comparison).