Just a bit to bright

You need to learn right away, to avoid bleeding money needlessly for your audio career, to fix the problem where it exists instead of using band-aids for flawed product. You can never solve the flaws in products with purchases of components that have their own severe colorations in the other directions. These are all distortions and they don't cancel out, they add up.

Not saying your speakers are way off neutral, but you need to know before you start building a mix and match system. Amateurs and experimenters will say that "it's all mix and match" but only to smaller degrees of you pick excellent products.

Borrow other speakers, just to see if indeed it is your speakers. Take yours to other places to plug them into other components to see if brightness follows you speakers or if it does not. Know exactly what you have before you start buying.

The above is coming from someone who has spent his life selling components to mostly audiophiles, and the occasional music lover (they are not the same), but hate taking money unless true improvements are the result. I've seen tons of money thrown out because folks have been attached to a flawed component. In the end, after spending tons of money, they then end up replacing the flawed component anyway!

Maybe your speakers are the problem. Maybe they are not. Find out what the problem is before buying anything.

I'd remove the NAD 326 from the mix. The right amp will make a world of difference. I'm so impressed by my most recent purchase of a bipolar Adcom GFA-5002. Heck of an amp! The 5XX series of older Adcom amps were bipolar as well as I have read. Adcom still makes new Bipolar amps. You should be able to resolve your very slight brightness issue w/a different amp/pre-amp/int. amp. Good Luck!

Since you built the speakers I would take the easy and least expensive step. If your tweeter is too hot, then replace the capacitor with a nice PIO type that will do wonders. I suggest Jupiter HT Flat Stacked. If you also have a cheap sand cast resistor, replace it with a Mills MRA.

This will do the trick. It will make you smile!

I would be happy to help if you need direction. This will impact your system more than wire or an amp change and allow you to keep your speakers.

It will not require you to buy, sell and ship gear.

Your speaker uses Dayton caps and resistors....oh yes the mod I mentioned above will do wonders!