I’m considering upgrading my speakers internal wiring

Before going forward I’d ask Peter what wire he used internally. He’s usually very good with email.

I doubt that he used some cheap THHN. Some Neotrch OCC or Mundorf might give you a different sound but you’ll never know if it sounds better to you or not until you try. Personally I used solid core Neotech OCC in teflon for my speaker internal wiring and like it very much.

I do have a pair of Peter's Liberty Audio B2B-100 amps and I did change the binding posts on those to KLEI.

If you want to do it do it. 

Sounds like a great learning experience. Make sure you dont go cheap on tools, especially crimpers and connectors

Stay away from crimp connectors from parts express, they are universally garbage.

Why don't you call him up and ask if he thinks that is a good idea. 

You have fully broken them in and know exactly what they sound like? If not make sure you have at least 500 hours on them and many of those listening. Cardas is likely to sound a bit warmer... is that what you want?

Asking the designer for his thoughts seems prudent if it’s an option. There may be more to the internal wire than meets the eye.

Most speakers use fairly pedestrian internal wire, and normally I’m all for parts upgrades, but in this case, I’m not so sure. He used a lot of really good crossover parts. On the other hand, it is reversible if you don’t like it, so if you’re up to the cost and time, that’s all that’s really at stake.