Last week I got a Boss2 in the acrylic case and am using it with a Pi 4 as part of a bedroom system. I'm very happy with it. I've experimented with Raspbian, Diet Pi, Picoreplayer, and Moode. All work. If you want to use vanilla Raspbian you'll have to edit config.txt for the correct overlay and shut off the built in audio. If you're unlucky you'll also have to configure the default ALSA device. Instructions for all are available on line. You can use VLC (included) or any of many other audio players but you'll have to have a display, keyboard and mouse connected to the PI or use VNC. You can also use MPD--manual configuration required--with a mobile device control app like MALP on Android.
The easiest setup for me was with Moode. You can do all the configuration within the Moode web interface. For some reason the Moode web interface performs very s-l-u-g-g-g-i-s-h-l-y on my Android phone and tablet so I use MALP. Moode is based on MPD. The Moode web interface works fine on a desktop or laptop PC running Win, Mac, or Linux. Also Moode has CamillaDSP. I listen at low volumes--well under 5wpc most of the time--so I set up a loudness contour filter that works nicely. I haven't succeeded in creating a usable convolution file for CamillaDSP but I'm still trying.
I've been using Moode for quite a few years and prefer the UI to others because of the availability of tweaks and the variety of renderer options. It's open source and has an active forum where you can get prompt advice from the developer and other people who know what they're talking about.
FWIW, I noticed some small improvements in SQ. Some music I've listened to often had a bit more detail and a somewhat better stereo image. My hearing is not what it used to be and I have the audiogram to prove it so I'm not the best source for this sort of information. I had been using HifiberryOS with a Hifiberry DAC+DSP with the same Pi4. It has a bare bones utility for room correction that involves recording a sweep tone at the prime listening point. My subjective impression is that the Boss2 sounds better.
My system is Pioneer Andrew Jones bookshelf speakers, a low end Monoprice 12" subwoofer, and an Elac 101EQG (now discontinued) 30wpc amp. It's not ultra-hifi but it's more than adequate for low volume listening. What I want is what Paul Klipsch described as the "good 1 watt speaker." With modern electronics the speaker is the most significant part.