Sensei I need advice

I have 5 Martin Logan electrostatics, 2 B&W on the sides and two subs(1martin). I have a Yamaha Aventage I am rconsidering replacing with a NAD. and a heavy 115 lb Sherwood Newcastle Amp that really changed the environment when I added it. Presently I am looking at a whole slew of NAD Receivers and I am truly lost on what to do next. A sales person at a store said buy our T748 Nad and your whole sound stage will change and nervana etc. and it can be upgraded later.   My Question: Do I need an amplifer to run my speakers or can I do this whole thing with one of pricier receivers? Or should I keep the Sherwood 7.0 amp and run the speakers through it.  I spent years throwing away money on systems and speakers and I do like the Martin Logans...they have been the best for me and I do like Theater movies and Concert DVD shows. Sorry to be lame here, but I am trying to avoid being sold.... once again and a need to start again.  Thanks for your imput.... Rik