The past few weeks I’ve been testing Toslink vs USB vs Bridge II with my headphones setup.
DS Snr > Oppo HA-1 > Sennheiser HD800-S headphones, with all balanced connections all the way through to the headphones.
All power cables (DC and AC) are unshielded and starquad config. I use one big powerboard which has no filtering or conditioning between outlets, with all devices plugged into this one big board, to help keep impedances between outlets as low as possible.
Just wanted to share my observations. Disclaimer: none of this was done in a scientific way. Software is Roon in bit perfect mode.
So the Toslink source is a Pi2Design 502DAC board on a Pi3, powered by an Uptone LPS-1 (an off the grid power supply, so to speak). Some highlights are a nice ultra low noise LT3042 powering a pair of NDK oscillators which help to lower the output jitter. A Lifatec glass Toslink cable is used (the shortest length they make).
For the USB source, I recently bought my old man (my dad) an iFi DAC2 (NOS DAC) to use with an ultraRendu so he can play with Roon’s DSD up-sampling. He’s been feeling left out and a little jealous about my DS I think, so he’ll be able to use Roon up-sampling to DSD256 with the iFi DAC2 shortly. So I used the ultraRendu to test in my system before I give it to him. This was powered by the Uptone LPS-1 also (off the grid). USB cable used is the High Speed certified 90-ohm spec Supra USB Cable, their shortest 0.7m length.
Now the Bridge II input is FMC isolated but recently I had the switching regulator replaced by a low noise linear regulator added and caps replaced. The DAC side FMC is again powered by the Uptone LPS-1. The router side FMC powered by a Mean Well 5V, nothing fancy. The DAC side ethernet cable used is BJC Cat 6, 1 foot in length from the FMC to the Bridge II.
Before getting the ultraRendu and tricked out FMC’s, Toslink has always sounded better than a direct USB cable from the PC or a direct ethernet cable from router to the Bridge II.
The ultraRendu is the best USB source I’ve ever had in my system (I’ve tried many of the popular USB sources) and for the first time USB sounded as good as Toslink in my system. I don’t know how this comes across, but I consider that a major compliment Ted’s Toslink input and DS’s jitter reduction considering the price of a nice glass Toslink cable vs the price of the ultraRendu. But I also consider it a major complement to Mr John Swenson for a really great USB source (USB signal integrity and all that fun stuff)
But for the first time ever, my tricked out Bridge II input (switching regulator removed and caps replaced and powered by the Uptone LPS-1) has beaten Toslink in my system, to my ears. I had previous tried the stock FMC’s powered by both stock PSU’s and by the LPS-1 but removing the switching regulator has made a key improvement (to my ears).
Now even though the Bridge II module has an I2S output, it is a little computer, like having a RPi3 inside the DS housing. I don’t know how much noise is generated by having this little computer inside the DS and how much extra ‘work’ is needed to power this and if ethernet signal integrity is as much a thing as USB signal integrity. There may be a tradeoff there with the Toslink input and my ears/brain prefer this tradeoff, compared with the (possibly) higher jitter of Toslink. All I have is my ears though.
Considering the cost of a nice glass Toslink cable vs an ultraRendu and vs the Bridge II with tricked out upstream components, the Toslink performance is quite incredible.
It’s been fun trialing but it’s time to pass the ultraRendu onto the old fella and enjoy the isolated Bridge II with Roon.
Even though the Bridge II is now the best sounding in my system to my ears, if someone were buying the DS and asked for my unqualified opinion of the best source, I’d say get a Pi3 with Toslink output and the nice glass Lifatec cable and be done with it. You’ll need to not only spend a lot more to better it (I think) but even then, all the interactions between cables and devices can vary from system to system, that copying one persons setup may not result in better sound in your own system (it could sound worse due to the funny interactions) - that’s the long version of YMMV.
It was a fun experience and something tells me it’s not over yet hehe.