I have a new Cambridge Audio CXA80 amp, with all the possible options for digital connection, and I want to use a Raspberry pi 4 as my streamer player, from my FLAC collection in my home server.
What is, in your opinion, the best option?
Should I connect the Raspberry directly by USB to the amp?
Or, should I add an HAT, and connect through Toslink optical or coaxial?
I will receive my Raspberry pi 4 tomorrow, so I will use USB right from the start, so my question is: Should I think about adding an HAT?
Well I would go thru USB but would use an ifi iPurifier (active filter, reclocker and rebalancer) or at least a passive jitter usb filter. Unless you invest in a high end HAT with its own clock and separate power supply, the benefit of using the spdif connection will be marginal and you are limited to the HAT bitrate (which will be mostly only 96/24). Also worth investing into a audiophile-grade PSU for the RPi.
I too have just started down the Volumio Pi 4 route. As you are probably aware the pi 4 is better than the pi3 for direct USB operation since the pi3 sometimes suffers contention between the ethernet port and the usb resulting in stuttering (esp. at high bit rates?). However most usb computer ports are electrically noisy. This noise can sometimes contaminate the audio output of the DAC (depending on the engineering skills of the guys doing the USB interface in the DAC - for example Chord Electronics do an excellent job suppressing this noise on all their DACs). This noise may cause the DAC to sound a little over bright and tiring to listen to. For those with access to spectrum analysers a residue 8kHz USB switch tone may also be observed on the DAC output. But first try it and see what it sounds like without any fixes. Novodar, above, suggests several worthwhile ways to clean up the USB. Another option suggested by Archimago is the use of a good quality USB hub as a buffer
Apart from its effectiveness you might just have one to hand!
At least with a raspberry pi you shouldn’t suffer ground loop problems that you can often get with a desktop USB feed.
I have borrowed an expensive USB cable and done a blind test against a modest quality cable - no difference. I decided to save money! But short cables are still probably best.
I’ve heard this too. Clock rate on the pi4 is marginally higher = more interference? It might have been better if the pi4 cpu had been fabricated in a smaller geometry CMOS process. This would have reduced the interference at the same clock rate if the cpu clocking is the issue. Would also have run cooler. But the best way to investigate this noise in the first instance would be to measure it, perhaps on the output of a really badly designed DAC. I do not believe this has been done.
True blind audio testing is quite difficult to get right and I’m not convinced this has been done either! I suspect that with a good DAC the raspberry pi would be hard to distinguish from an audiophile streamer.
