Why is SQ worse with an iFi Power to my Pi with Digi+ Pro?

Hi, I added an iFi Power to my Pi with Digi+ Pro running Roon bridge and the SQ was worse than with a normal PS. Is this normal? Here’s the background: originally I connected a Digi+ Pro via optical to a Metrum Pavane DAC with great results. However, being curious and because the optical connection maxes out at 96kHz on the DAC, I tried coax RCA out from Digi to BNC in on DAC via an S/PDIF cable. The result was crackles and pops (even though the network connection was good). I then tried a 5V iFi Power unit, which successfully eliminated the noise but produced noticeably inferior SQ compared with the Digi+ when powered from a 5V 3A 3000mAh power supply. Where do I go from here? Is the iFi Power unsuitable for use with the Digi+ Pro running Roon? Do I need to remove a jumper somewhere or solder on a BNC? (I’d rather not.) Maybe I should send the iFi back and stick with optical? Any ideas?

I added a iFi Power 5v to my HiFiBerry DAC + Pro, upgrading from the standard supply purchased from HiFiBerry. Didn’t notice any change whatsoever in my setup. Maybe you have a bad PS. It happens.

Hi the iFi iPower isn’t a LPS, it’s a switching power supply, but it’s a great low ripple noise one, especially for the price.

I had an iFi iPower 5V with a Digi+ Pro also without issues.

What BNC to RCA digital cable are you using, just out of interest? I wonder if it’s that. Can you connect the Digi+ Pro directly to your DAC’s digital coax (RCA) input, instead of the BNC input? So that it’s an RCA to RCA digital coax connection.

If not, then I would definitely report it to iFi - they have great customer service. Try that before switching back to optical.

Hmm thanks I was thinking along the same lines. Don’t have any other S/PDIF coax cables around but maybe I should try to get one to check before I go any further. The cable is this one. Does it matter which direction it goes in (previously I used it the other way round)?

No problem. Shouldn’t matter which way it goes around. That same cable was fine and working with your battery 5V power supply right?

Hmmm if so then maybe it isn’t the cable. Hard to say. Try an RCA to RCA digital coax if it’s not too hard to get one.

Then got into iFi and tell them you’ve tried all the combinations.

I also wondered if it’s groundloop issues, which are eliminated when you use battery power supply and also eliminated with Toslink but the Digi+ Pro’s digital coax output is galvanically isolated (transformer isolated)

It’s a head scratcher

If you want to connect to your DAC via BNC, you may want to consider the DigiOne board by Allo. It’s an excellent transport and it comes with a BNC output by default, allowing you to maintain a proper BNC-to-BNC connection.

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Yes next step find an RCA/RCA. I used the cable not with Digi but between Naim NDX and a Mojo. With reference to galvanic isolation I read that you have to open a jumper:
“If your DAC is grounded (…), you can take advantage of the Digi+ Pro’s transformer-isolated output on S/PDIF over coax or BNC. To do that, simply open the jumper on the board.”

Thanks I’ll look into this, although ideally I’d like to go AES. From what I’ve read though it takes big bucks to get a significant improvement. Open to suggestions…

Thanks again, this looks great. In fact maybe I’ll just go USB and order the USBridge! Do you know if the iFi Power supply will be useful with this? Cheers, William

For testing you can just use a standard audio RCA/RCA interconnect. It should at least tell you if the RCA/BNC path has issues.

(Your Pavane has a pretty good USB receiver, but I’d bet it still sounds better on S/PDIF if you can get it working right.)

I have one of these, has AES output, works like a charm. No affiliation.

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Thanks for this. Spoilt for choice now :slight_smile:

Oh fiddlesticks I already preordered a USBridge :open_mouth:

At these prices, it may well pay off to be a little adventurous… :smiley:

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Yes, just to update, it was the cable! No more crackles or pops with a different RCA to RCA using normal PS, and after adding the iFi Power it is doing its thing as it should. Cheers, William

Fantastic ! Now, the most important question… how does it sound ! It should be awesome !

Well this is just my first impression, and it’s day time with the window tipped open, but it’s very good. To be fair, I was already getting good results with optical and most of my music files are in iTunes lossless 96kHz format anyway, but… there is more detail in the bass (on Morning of the Carnival on Larry Coryell’s Spaces Revisited album) and more separation (Birds on Coldplay’s Headful of Dreams). Definitely not disappointed but early days and more testing to do having ordered the Allo DigiOne for BNC/Cinch AND USBridge for USB. :smiley: Thanks and cheers, great forum this. William