A:AnswerThese are comparable to the Bose companions except there are bass and treble controls so you can turn down the bass. I've owned both sets of speakers.
A:AnswerThe powered speaker connects via RCA ports (includes RCA -RCA and RCA -headphone cables). if your preferred DAC has those outputs, I don’t see why it wouldn’t work.
The second speaker is powered off the first and connects with standard speaker wire (included).
A:AnswerMaybe. "Record players" have strange EQ and output levels compared to modern standards, so it may sound ugly. But the inputs are standard RCA plugs, so you can certainly connect them up.