I don't think the new NHT's are as warm as the older Supertwo's which the ST4 replaced. NHT switched to a metal dome tweeter that makes for a brighter sound. I have compared the Superzeroes, Superones and Supertwo's to the newer SB-1s. All the speakers in the "Super" series used the same soft dome tweeter and I am assuming that all the speakers in the "SB" series use the same metal dome tweeter. If I am wrong about this, someone please correct me. I am not a fan of bright speakers either so my recommendation is that if you like NHT, go with a pair of Supertwos over the ST4. Good luck.
-Kevin
-Kevin