Take note of the Knobloch CXs and the Rubinos as to how well/poorly they progress as you fret towards the body. Do they lose their energy over the body? Do the trebles maintain 'juice' all the way to the end of the fretboard or begin to sound thin? I expect the Rubinos will maintain their energy to the end. There are #3 strings that are unacceptably dull/tubby, and others that have enough clarity for me to judge them as being 'smoky', which is ok, if there is an acceptably smooth progression across the strings.

If you're seeking a brighter third string than the CXs, you might try a Savarez
Alliance; beyond that, one of the wound thirds. It's hard to make a monofilament third string that acts like a 'perfect' string, and a classical gtr has
a lot going on in that region that can cause a blurred sound, anyway.

As soon as the Knoblochs break in, I’m going to try a D’addario composite 3rd.
The only wound 3rd I’ve found is a ghs. Are there others?

Savarez makes one or more. Interested in what you think of the D'Add composite, too.

I like the feel of the Savarez Alliance treble strings, but the 1st string tends to have a pingy sound to them.

I suggest that another option is to try the Oasis carbon trebles.

I've been using them with the Savarez Cantiga basses on my guitars and still enjoy the sound... It's a nice full rounded sound.

Dave

I’m curious to know where you guys are getting your strings.

I like experimenting with strings, but I’d prefer not to need to pay $5 in shipping for a $6 set of trebles.

I get all my strings from Strings By Mail... They're a supporter of this forum

They're the only string supplier that I am aware of that sells separate bass and treble sets.

When I place my orders, I tend to purchase several sets of Savarez Cantiga normal tension bass strings & then experiment with purchasing various makers trebles sets when I place my orders.

Right now, my preference is Savarez Cantiga Normal Tension Bass strings matched with Normal tension Oasis carbon Trebles.

Since bass strings wear out much faster than trebles, this process works for me.

I've had the D'Addario composite third on for a few days now. To my ear, it's not as crystalline as the Knobloch CX third.

Sign up for emails with Strings and Beyond. They regularly send free shipping or 15% off email offers. I know the 15% off won't be of much help on a $6 set but the free shipping offers would.
I imagine the other string vendors do similar.

Check out Martin's 'Magnifico' strings....they've blown my mind! A result of Martin-Aquilla collaboration, they're similar to Runbinos but are not exactly the same...

my experience has been that the trebles settle into pitch faster than any string I've ever played, and the tone is THE tone I've been seeking on nylon-string guitar for decades...I've played guitars, violins and banjos strung with gut and they sounded amazing, but gut has so many practical disadvantages....

The Martin Magnifico strings sound very gut-like to my ears.

I now want to investigate the Aquilla string line, to see if any of their offerings are similar to the Magnificos, chiefly because Aquilla offers partial sets, and the bass strings always need replacing more often than the trebles.

I'll definitely give these a try soon.

The Rubinos only come in one tension, but the Magnificos come in two tensions. Which tension is most like the Rubinos?

I've been using the Aquila Rubinos for a little while no and I think I like the Knobloch CX Actives a little bit better. The CX Actives are just a bit crisper and brighter.

Quickstep, what is your guitar?

Broke the E and B Rubinos during installation—probably should have tuned up more gradually. So only got to play the 3rd string but after restringing with the CX's I’m really satisfied with them.

The rubinos are softer strings, so if there is anything sharp at the nut or the saddle, they may cut.