I started, as a lot of us did, with a Pi 3 Model B and after much faffing and farting around with it, managed to improve upon the basic setup by rewriting the configuration file contained within the Volumio software. Long story short, I throttled back virtually everything that could be throttled back and shut down stuff like HDMI that I wasn't using. Less is more, as we all know.
From there I went to an Asus Tinker Board (ATB), which gave me a better sound, but no flexibility as far as rewriting stuff went. No matter, it sounded good.
I've recently bought a new DAC as mentioned elsewhere and decided to go into full "experimentation," mode. All the way through I'd been using a USB connection to my DAC, so I thought I'd see (or hear) what the other options sounded like. to that end, I bought a HiFiBerry Digi2 Pro and a case to go with it, which gave me an optical and a 75Ω coaxial output to play with. The first thing I discovered was that the Digi2 Pro wasn't compatible with my ATB as I half hoped it might be. I know some of the HiFi Berry kit is.
No matter, I'd planned for this, and I'd already decided that if it didn't work I'd just get a Pi 4 Model B.
The next thing I discovered was that between the Pi 3 and the Pi 4, Raspberry, Gawd bless 'em, had decided to completely mirror the USB and RJ45 ports on the "front" of the Pi. My twenty-quid case was now a twenty-quid lump of metal.
I ordered the Pi 4 and a new case (£22.00 this time) and I got the Pi and an apology that the cases had now gone out of stock. I'm still waiting. It was either that or pay £15.00 over the odds at Amazon.
Anyway, back to the *stifles a yawn* exciting stuff.
I slapped the HiFi Berry Digi Digi2 Pro onto the Pi 4 and started testing, sans case. To cut a long story as short as I can, after a lot of to-ing and fro-ing I was surprised to find that I actually preferred the sound of the optical connection. Again as detailed elsewhere I bought a posh optical cable and I've just hooked it up.
Now. I. don't. want. to. go. overboard. but...
I have to take into account that although an optical cable will not need "burning in" my DAC hasn't yet got many hours on it, and so, technically at least, it's going to get even better.
I bunged my favourite Rostropovich JS Bach Cello Suites on and it sounded rather good. It's lost some of the "rawness" I usually associate with the recording and has become a tad more polite although not in a bad way. I think I'd just got used to hearing it the other way.
This new sound makes me smile.
At least, it does now that I've unleashed my secret weapon. I've rewritten the Volumio config.txt for the Pi 4 as I did for the Pi 3, with the help (all right, technically I cribbed some of his work) of our old mate Archimago. One extra I added myself was the shutting down of the USB ports as I'm not using them. Everything is throttled back and it was probably the extra 5% in quality I wanted.
For anyone with a Pi4 who wants the new config.txt, here it is.
For anyone who wants my updated Volumio config.txt for the Pi4 here it is.
Standard warning: If you don't know what it does, and/or you don't know how to change it, you're probably best off ignoring it
More info here http://archimago.blogspot.com/2020/10/musingshow-to-raspberry-pi-4-touch.htmlinitramfs volumio.initrd
gpu_mem=16
max_usb_current=1
dtparam=audio=on
audio_pwm_mode=2
dtparam=i2c_arm=on
disable_splash=1
hdmi_force_hotplug=1
# Archimago's CRAAP Pi 4B Settings...
# h #ttp://archimago.blogspot.com/2020/10/musingshow-to-raspberry-pi-4-touch.html
# October 14, 2020
# CPU speed control - normally 1500MHz, min 600
arm_freq=1200
arm_freq_min=300
# CPU voltage control - SYSTEM DEPENDENT!
over_voltage=-3
over_voltage_min=-4
# SDRAM control, normally 3200 - again, watch system dependent voltage
sdram_freq=2400
sdram_freq_min=300
over_voltage_sdram=-3
core_freq_min=200
gpu_freq_min=200
gpu_mem = 256
# Keep it cooler! Throttle at max 75C.
temp_limit=75
#Overclocking Options
force_turbo=1
avoid_pwm_pll=1
sdram_schmoo=0x02000020
over_voltage_sdram_p=-5
over_voltage_sdram_i=-14
over_voltage_sdram_c=-6
disable_pvt=1
#Force max current to USB
max_usb_current=0
#HDMI Disable
hdmi_blanking=2
#New Power Saving
hdmi_ignore_hotplug=1
hdmi_ignore_composite=1
#### Volumio i2s setting below: do not alter ####
dtoverlay=hifiberry-digi-pro
If you're tempted to give it a go don't forget that if you're using a USB DAC you really don't want to disable the USB ports.
So, delete this bit...
And that's where I am, currently. I just need the case to tidy it all up now.#Force max current to USB
max_usb_current=0