Hi FR,
I haven’t done the direct comparison you refer to, but I heard a ZenithIII (with and without Phoenix) direct over USB into a TT2 and good headphones on the Innuous stand at Bristol this year - it was playing using roon/squeezelite mode - and it was genuinely very good, with a slight improvement via Phoenix, vs. without Phoenix [for me these various enhancement products such as Mscaler, Phoenix, Audiophilleo, Mutec etc. need a good DAC and analogue side to the system to make a difference).
I would say for pure music playback over USB into my own TT2 at home from locally stored music that the Melco N1ZH/2 (which I had myself at the time - the same model you have) was slightly better than the ZenithIII, but the Zen/Zenith has far greater flexibility as a server; in my case I have combined a Nucleus+, Mutec USB, and Melco functions into one capable box (maxed out ZM3) plus the tiny Rendu, and clawed back some money & rack space in the process. I have to say that my Melco/Nucleus dealer and Melco UK were very supportive when I had to reduce my system 9 months ago due to the Covid downturn - a tight community.
Before the TT2 I had a Hugo2, then the Hugo2 with MScaler, and that combination (in my own system) was certainly bettered by the ‘bare TT2’ in a back-2-back comparison- so I traded the H2/Mscaler combination for the TT2.
The TT2 is expensive, and has ‘redundancy’ in the headphone/pre-amp if one is not going to use that - I actually feed two analogue pre-power setups in adjoining rooms from the two pairs of analogue-outs on my TT2 - and I use it as the DAC from my TV as well as the Rendu - so apart from headphone usage I am making best use of it. The ZenMiniII is right now sending a roonready stream to the TT2, to my Atom, and to Qb2 - the house is filled with ‘Naim Radio’ today -:_
If @mikehughescq wants to continue the digital journey, i.e. a simpler system without analogue and the CD player, then a TT2 is a capable pre-amp for Naim and particularly Chord amplification - saving a lot of box-count, interconnects etc - see the running thread Qutest, Hugo TT2, Mscaler
A further alternative to reduce boxcount, even without a separate DAC, is to go ‘fully active’ with the speakers - e.g. Buchardt A500, Kii Three, Dutch&Dutch 8c - for another thread I suspect.