External DAC for Cambridge CXN (V2) and Sony XA 5400 ES

The Sony was Stereophile A+ rated in 2014 which is probably prehistoric in digital years although still wonderful, especially on Redbook.  The Cambridge is excellent too although if I rated the Sony @ 100 the Cambridge would be 97 with extremely slight detail differences and a background that's just not quite as black.
I'm wondering if a nice external DAC would give me a detail and depth of stage boost?  I'm considering a Benchmark DAC 3 b to feed my Audio Research vintage (tube) pre-amp although Mytek (Liberty and Chord (Qutest) seem to have highly rated offerings.  Benchmark has a 30 day trial offer that might work as I'm well past the point of buying anything I can't hear in my room.. I'm leaning towards the Benchmark for the trial offer and I don't need a volume control since the AR pre has a remote volume.
Opinions?