I had the LS 16 while I was waiting for my LS 25 MKII. This is THE upgrade. Bass response is in a different league all together and the preamp is much much quiteter. It makes a big difference. Thankfully, it retains all of that glorious ARC sound. Not bright but a fully extended high end. There are only 2 tubes to worry about, the REF 2 has 11.