Guarneri is more refined, more detailed, richer and more suave in the midrange and highs, and has better soundstaging focus and scale, has a more relaxed sound and laidback bass. It is easier to drive and is more docile sounding than Auditor.
Auditor has more forward upper mids and highs, but a bigger and more spacious soundstage as well as a more dynamic and livelier disposition, as well as a punchier upper and midbass. It is harder to drive and a lot more choosy when it comes to matching electronics.
If you listen solely to refined acoustic music as well as vocals then Guarneri is better but Auditor is more versatile and can play more types of music with surprising power and punch.
