I'm afraid that I cannot comment on the 15.0, as I have never heard it. I have owned many audio products over the years, I owned CODA Model 10 and Model 20 amps in the 1990's. After climbing up the almighty audio food chain for many years, I have finally gone back downstream due to the economy. I am living very happily these days with a VAC preamp and CODA Model 11 amp.
I won't bother to say that the Model 11 is the best amp I have ever owned, because it isn't. I will say that it is a very musical amp though, especially for a solid state amp. Yes, certainly not the last word in transparency, but never irritating or aggressive, always pleasant to listen to. Just as I recalled the Model 10 and 20 amps from the 90's. It's one of the reasons I went back to CODA when downsizing.