ND5 XS to NAC-N 272 with Nait XS 2

I’ve upgraded from an ND5 XS to a NAC-N 272, still using the power amp section of the Nait XS 2.
One oddity is that the Nait still requires a power supply for the pre-amp, even though the audio is going in through the Power Amp In 4 pin connector (I conclude this actually connects to the last stage of the pre-amp).

Summary Overview

Positives: Many subtle improvements (detailed below), slight increase in PRaT, slightly firmer perceived bass presentation (no change in actual bass volume),

No significant change: Little change to overall presentation, retains the same sense of vitality and musical involvement. (N.B. as I was happy with the ND5 XS but wanted more detail and descrimination in the sound, so this is a positive result.)

Drawbacks: Increased cost (but justified by the more accomplished performance).

Details (and exemplars), compared to the ND5 XS
These points are generally true, applying to most music; each of the pieces quoted below are just specific instances that demonstrate the characteristic.

Much more discrimination of vocal presentation

Karl Jenkins, Adiemus; Adate Adea
This piece uses vocal and orchestral counterpoint, and the threads of the counterpoint can all be followed more easily.

Urbach & Bettgens; The Broken Lines Project: “Butterflies”
At several points, Urbach sings in unison with herself, the 272 easily resolves the two separate instances of the one voice, despite the fact that they are the same person singing the same note at the same apparent location within the sound field.

Much better presentation of orchestral timbres

J. S. Bach, Brandenburg Concerti; all (Dunedin Consort)
The ability to follow the counterpoint is much improved as the distinct characteristic sound of the individual instruments is better preserved. Instruments have less of a tendency to ‘disappear’ into a generalised sound field.

A. Corelli, Concerto Grosso No 4; IV (Avison Ensemble)
The ‘growl’ of the aggressively bowed ‘cellos at the end of the movement is better preserved.

 
Significantly easier to ‘hear the words’ in vocals (readability)

Karl Jenkins, Adiemus; Adate Adea
The words can easily be distinguished in each singer’s voice.

Mirabilis, Here and the Hereafter; Here and Hereafter
The voice (of a passed loved one) is set back in the acoustic. The better resolution of the NAC-N 272 allows the lyrics to be understood much more clearly.

Greater delicacy of presentation

All my Faith Lost, Redefine My Pure Faith; Dulcinea
The delicate interplay of the voice and accompaniment is presented with much more finesse, there’s a greater sense of air and a calm stillness.

Greater Orchestral scale

H. Berlioz, Sinfonie Fantastique; 4th & 5th movements (Concertgebouw)
The drama in the last movements is driven by a greater level of presence.

Improved portrayal of ‘mood’

Kara, Waters So Deep; Made of Light
This is a song about loss, and the sense of loss portrayed is yet more palpable here.

Ari Mason, Songs of Desire; The Curse
This uses syncopation and a set of ‘uncomfortable’ tonal transitions to produce a disturbing and disrupting effect, there is a small increase in the strength of the effect.

Mirabilis, Here and the Hereafter; Here and Hereafter
The pathos is and sense of loss are more strongly portrayed

I’d liken the change to be similar to upgrading your seat at a performance in an auditorium: Upgrading from a seat at the side to one that’s central. It’s the same music, but you’re so much more aware of the many nuanced subtleties in the performance.

Numerically controlled volume control

Another useful advantage is the numerically controlled volume control. This allows me to accurately set a volume before starting to play a piece:
Music Type : Volume Setting
Large scale classical needing oomph: 42
Small scale classical: 35
Modern pop / rock / electronica, set at correct transfer level: 35
Modern pop / rock / electronica, mastered for MP3: 27
Modern pop / rock / electronica, encoded as MP3: 0 (and stays at zero!)

Anyway that's my findings in my system, other people may well observe different things according to their listening priorities.