Abe, I've owned 1.5s for several years and recently went to 2.3s. While I felt the 1.5s were generally more tonally faithful than the 2.3s, the latter has a bit more weight on the bottom end. From the mid bass up, these speakers are fairly similar. The 1.5 is just as smooth as the early 2.3 - the revised 2.3 is a wee bit smoother, but not enough to justify tossing 1.5s. If you ever move up from 1.5s (which is a fairly manageable load) be prepared for a MUCH larger current draw with the bigger Thiels. Be sure your tube amp is up to the task or you may be very disappointed. Thiels in my experience require careful partnering and tend to sound edgy or bright when mated to SS amps with inadequate current reserves. Not as much of a problem with tube gear, but you may find dynamics and bass compressed and restrained if you don't have the horses. I will say this, if you do it right, Thiels are spectacular performers.