Well, the Radio is (sadly) the only Squeezebox device still in production these days. DAC is the TI TLV320AIC3104.
I calibrated the headphone output to my E-MU 0404USB, WiFi streaming, measured with the usual i7 workstation.
Not expecting hi-fi performance out of this unit of course and pretty
well got what was expected... Overall, an OK performer in the 16-bit
domain for music streaming duties and incapable of taking advantage of
24-bit audio with only a measly 1dB improvement in dynamic range.
It's a "radio" after all...
For posterity and completeness, here is the SB Boom.
Internal DAC is the TI TAS3204.
Like with the Radio, this was connected from the headphone out in the back --> E-MU 0404USB, WiFi streaming.
Again, not a hi-fi unit by any means. Good dynamic range but stereo
crosstalk is a bit on the high side. Like the Radio, you can see a
slight improvement with 24-bit data but not much of an improvement to
call it worthwhile.
It sounds great as a stand-alone system which is all I really use it for in the living room.