Either the Naim amp boxes are wrong, or the room is wrong. Spending a couple of thousand on Fraim and speaker cable just shouldn’t be a requirement to make it a pleasant listen.
Yes, a NAPSC and HiCap would be icing on the cake, but they won’t remove unpleasant harshness.
I would consider changing the 102 for an 82 if you want to stick with ‘olive’ Naim amps. Then maybe add a Hicap.
Beyond that, improving sources is always beneficial, and you have an amp which is revealing enough to show off source improvements very clearly.
Are you sure the components are all properly set up? Are they on a dedicated rack, or at least on shelves with no boxes stacked on top of each other, and cables properly dressed. Are you using Naim-compatible speaker cables? All these details added together can make a big difference.
If it’s any help, my 2nd system consists of a CD5x 72 hicap 180 into small Mordaunt Short stand-mounted speakers, and it sounds just fine
It would seem that some folk simply can’t really get on with a 102, the sound will never be what they’re looking for. Putting a hicap on the 102 will create the same dimensional upgrade improvement in audio quality as any other (suitable) pre-amp, but the defined nature of the 102 will still continue to shine though, accepted by some and disliked by others.
Buying a 72 for your 180 is probably the most cost effective way to change the sound to what you may find far more agreeable, and with a musical sound keeping you contented for years, not as detailed as a 102, but classic 72 warmth and emotionally musical to keep your feet tapping and your face grinning.
Upgrading to 82 is okay albeit more expensive, and possibly a slippery slope for later day upgradious; two hi-caps, a supercap, a 52…