Upgrade suggestions from Arcam rDAC

Looking for advice on DAC for Volumio on rpi 3, currently using an Arcam rDAC. Ideally a HAT DAC but not sure how realistic it is to expect a HAT DAC to be better than a standalone unit like the rDAC?

I have already compared a Hifiberry DAC+ Pro side-by-side with the rDAC. I tried them both connected to my Arcam A85 amplifier driving a pair of Monitor Audio C180 ceiling speakers. The source is some ripped CDs on a USB drive connected to the rpi.

Finding #1 - the rDAC output is a tiny bit louder (I think this may be consistent with published output figures of 2.1Vrms for the rDAC and 2Vrms for the DAC+ Pro?). I’m not worried about that.

Finding #2 - this is perhaps subjective, the rDAC sound reproduction seems clearer. The DAC+ Pro does a good job, but when listening to the rDAC, individual instruments seem to stand out more within a piece of music and the overall experience feels more “lifelike”.

So basically I’m wondering if there is something better still than the old rDAC, any suggestions? It’s ten years old (cost about £400 10 years ago, which I guess makes it a mid-range system?) which seems a reasonable time to expect technology improvements.

I feel like you’d see a better improvement by going to a Raspberry Pi 4 with your Arcam rDAC, than you would by changing to a DAC hat.
The USB on R Pi up to and including 3B+ isn’t good for audio, so you are compromising the ability of your rDAC if it’s USB connected.
A DAC hat (I believe the Allo Boss V1.2 is better than the HiFiBerry), gets around that USB issue and is quite a decent DAC, but possibly not as good as a separate hi-fi component DAC.
You could try an Allo DigiOne hat, that gives a coaxial S/PDIF output to feed the coaxial input on your rDAC. That should be better than a USB connection by a good margin.