Supratek Cortese Phono Tubes Help

I have a Supratek Cortese that I purchase new a year ago form Mick.I am using the stock tubes that came with it ,except for the 6ns7 I am using KenRad Dark Glass. I also purchased a pair of Chinese Valve Art KT66 to try in place of the Sovtek.
I am happy with the sound of the Cortese, I would recommend anyone with the latest style Cortese to try the KenRad’s they have better base and add a little more weight with extended highs.
My question is - is it worth it to upgrade the phono tubes , I have the Phillips.
Can I get the same type of improvement that I got changing to the KenRads ?
If I can then what is a good tube to get for $200-$250?
You can do alot better than Phillips in the phono stage. The Sylvania VT231 are reasonably priced at $100 a pair, the Sylvania WGTA are dynamite at $119 a pair, and the Russian 1578 may be the best tube for 6SN7 ever made at $249 a matched pair.

The tube you want depends on your system and musical bias.

Disclaimer: I am a dealer of NOS tubes, so take my comments for what they are worth.