This is a review and detailed measurements of the Periodic Audio Rhodium DAC and headphone amplifier/adapter. It was kindly purchased new by a member and drop shipped to me. It costs US $99 but company has it on sale for US $49.
The Rhodium looks like any other USB-C phone dongle:
It was plug and play on my Windows 10 PC and that is how I tested it.
Rhodium DAC Measurements
As usual, I test these dongles as DACs (with high impedance load) so that we can assess its performance without the headphone amplifier portion (even though it is still in the loop):
Ah, this is not very good. Third-harmonic is quite high at nearly -81 dB which dominates the SINAD to the same tune. Output voltage is only 1 volt which means it will not have much power to drive high impedance headphones either.
Jitter test showed nice, flat noise floor but some data dependent jitter (due to 250 Hz square wave in j-test signal):
Most important test here is amount of power so let's start with 300 ohm load:
As suspected, there is not much power here:
Switching to 32 ohm load we get:
Company spec is much higher (around 35 milliwatts). Maybe that is one channel with much more allowance for distortion.
Listening Tests
I tested the Rhodium DAC using my Sennheiser HD-650. On tracks with full amplitude, there was enough volume to enjoy so dynamic power should be higher than shown. But on any track with less than max digital levels, I didn't feel there was enough volume there.
Conclusions
I met the company at an audio show and was impressed with their objective approach to headphone design and measurements in general. I am therefore disappointed to see such a low performing dongle sold at rather premium prices. I hope they can upgrade the platform to something better.
As is, I can't recommend the Rhodium DAC. Hopefully I don't loose another professional colleague in the industry over this review.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The Rhodium looks like any other USB-C phone dongle:
It was plug and play on my Windows 10 PC and that is how I tested it.
Rhodium DAC Measurements
As usual, I test these dongles as DACs (with high impedance load) so that we can assess its performance without the headphone amplifier portion (even though it is still in the loop):
Ah, this is not very good. Third-harmonic is quite high at nearly -81 dB which dominates the SINAD to the same tune. Output voltage is only 1 volt which means it will not have much power to drive high impedance headphones either.
Jitter test showed nice, flat noise floor but some data dependent jitter (due to 250 Hz square wave in j-test signal):
Most important test here is amount of power so let's start with 300 ohm load:
As suspected, there is not much power here:
Switching to 32 ohm load we get:
Company spec is much higher (around 35 milliwatts). Maybe that is one channel with much more allowance for distortion.
Listening Tests
I tested the Rhodium DAC using my Sennheiser HD-650. On tracks with full amplitude, there was enough volume to enjoy so dynamic power should be higher than shown. But on any track with less than max digital levels, I didn't feel there was enough volume there.
Conclusions
I met the company at an audio show and was impressed with their objective approach to headphone design and measurements in general. I am therefore disappointed to see such a low performing dongle sold at rather premium prices. I hope they can upgrade the platform to something better.
As is, I can't recommend the Rhodium DAC. Hopefully I don't loose another professional colleague in the industry over this review.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
