Ok I have a pair of of very early SDA1s (1983). In extensive listening I and others liked the sound of the RTA12bs more then the SDA1s. It was felt the RTA 12Bs had more depth out in front of the speaker and a somewhat more dynamic sound verses the SDA1s slightly soft and laid back. HOWEVER I am not willing to give up the ship yet. There is a pair of SDA1Bs in my area. The desgin is changed enough to wonder if it is worth a try. It is a risk. Opinions on what differences i might hear between the SDA1s and the SDA1Bs. HELP!!