JR - The 'real' beauty of Mana is the Phasing approach , I had similar reservations as you, believing the whole glass/spike combo was bound to lead to an aggressive HF & Vocals. Quite the opposite though in reality.
The LP12 loves Mana, but I believe a holistic approach is the best way - i.e. get all Naim gear, Mana Supports, and Music Works Leads...
The most effective Mana Route is an Amp Rack, then just keep adding SStages - BUT DON'T forget your speakers (what are they ?
Now some ramblings regarding my Mana Experience
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* I started with a basic rack (6 Tier), it replaced my Sound Org (snap ehh), suffice to say after the usual first-timer set-up teething troubles, the Mana really left the Sound Org for DEAD (it can be a pain in the arse (at first) but correct set-up is important)...
* Next I went Phase 2 on the main rack and Phase 1 for the Intros -
The difference again was very noticeable, as you mentioned 'more' of the same really, but the Intros responded well to my surprise.
* Next, was Phase 4 to the main rack, and Phase 2 for my SBLs -
This is were it really starts. With Mana there appear to be 'sweet-spots' Phase 4,7,9 (yep, I initially thought it was a plot to sucker you into the rack thing - WRONG) - PHASE FOUR was a revelation rather than becoming bright and forward the sound became smoother and more listenable (weird) everything improved but Bass/Vocals/Detail excelled the most.
* Next, was phases 5, more of the same, then Phase 7 Main Rack and Phase 3 SBLs -
WOW my poor SBLs started really working now (poor buggers got the crap kicked out of em - but made me realise how good a speaker they really are) - 7 (heaven) was another milestone, again significant improvements everywhere, but the whole presentation took on the 'effortless' quality which players like the cdi/cds/cds2 do so right - things just fall into place perfectly - AT THIS POINT I DID'NT UPGRADE FOR MONTHS !!! - The room filled with music, and air around everything - it was audio nirvana.
* Anyway next (Rico's fault), I went Phase 8, and rapidly to Phase 10 !!! - Out of Box Experience, Bass How Low Can you Go, and Relentless PRaT...
What I thought for years were some ambient type transients, have developed to full solid instruments providing that background ambience that makes everything Ooohhhhhhhhh Soooooooooo RIGHT. Vocals are 'life-like' a real there 'she' is type thing, Feels like I've just replaced my 140s with 4 *250s the extra grunt drive, low end end clout is overwhelmingly better, but alas the SBLs are taking some severe PUNSIHMENT.
Where next ??? - nowhere quickly - Phase 10 'will' keep my smiling for some time
Phase 10 is very imposing and I suppose the WAF, GAF factor is important...
The best upgrades I've made in order are Mana, CDi, IXO, SBLs
naheed