I haven't used Roto 66s in about 30 years. I liked them, but liked other flats more.
Just yesterday, I put a set of D'Addario Chromes on my Portameto.
I only have about an hour playing time with them, but really like them so far.
Nice feel, and they're darker and thumpier than the Ernie Ball Cobalt flats I had on before them.
Have you ever tried Chromes?
My Portamento.
View attachment 4901364
I was trying their rounds. Not sure exactly which - but whichever ones Jaco used. Hence the experiment.
I'm not a big fan of Chromes too stiff. I have TI JFs in the case as well, but the fretless Jazz goes so well with rounds , imo.
And yes I agree nice bass! I'd still like to try one of those one day.