Shinealight:
I've owned the NAD C352 for many years and only recently replaced it with Ayre components. It's very similar to your C326 in design, and it's anything BUT strident, overly bright, and lacking bass. I'm also using 90dB two-way speakers. The NADs typically understate their power ratings.
IMO it's entirely possible that your new NAD will provide you with better fidelity and performance that you may not have "dialed in", yet.
Assuming you've already double-checked these items:
- Make sure your speakers are not wired out of phase (a classic for "tinney" sound and losing bass), reclean all your terminal contacts, and double-check integrity of speaker wires.
-Revisit your amp settings for tone controls, soft clipping, etc.
If you have any flexibility on location, go thru speaker placement exercises again. Maybe speakers closer to back wall will give you some of the extra bass response you need.
When we upgrade to better resolving systems, sometimes room acoustics issues that didn't really matter before now become apparent. So it's a good exercise to also revisit the steps for optimising listening position, room bass effects, etc., after significant upgrades.
If it still reeks and you've already allowed a long burn-in, then suggest taking the amp to your dealer and A/B this amp against one of his 326's in a demo system setup.
Other options: the NADs are truly the Swiss-Army-knives of integrateds. Easy to isolate the pre- and amp sections to
test with other amps, or to bi-wire, or bi-amp, or to add a powered sub to your system.
Whatever the outcome, good luck!