The cap up grade in the 4Bsst/2 took off the bright glare when compared to the sst model. It has really nice low volume playback and offered me better control of my volume control. The 14B has more upgrades in the sst/2 series than the 4B. The new 14Bs use a new transformer from Torus. I didnt own a 14sst but i can only imagine the difference is larger in upgrade from the 4B perspective. I can tell you that the new 14Bs play excellent at all volumes.