Does Bi-amping really make a difference in sound?

I have really been torn in the past week in how I should improve my Home theater stereo System. I presently own the following gear:

Oppo Blu-ray Player
Yaqin Tube Buffer (w/ 6SN7 Tung Sol Oval plate Tubes)
Cambridge Audio DAC Magic
NAD C-375 Integrated Amplifier
PSB Synchrony Two loudspeakers
Nordost Red Dawn Ics
Audioquest VDM-X Digital Cable

An experienced audiophile and design engineer who designs speakers and custom electronic gear has told me that in order to improve my sound drastically I need to Bi-amp my speakers. Since PSB speakers have separate crossovers for the tweeter/mid and bass, that I could take advantage of this and bi-amp them and really make them sing.

I was told that I should buy a another amplifier and use the Pre outs of the NAD C-375 Integrated amp and even tailor my sound by selecting the appropriate amp with the same power wattage.
I am thinking of getting an NAD C-275 or the Vincent Audio SP-331 Power Amp to connect to the Pre outs of my NAD C-375 and bi-amp my speakers with two sets of Harmonic Technology Melody cables running shotgun to my speakers.

I also plan to upgrade my digital cable to the HT Digital Silver cable and maybe the HT Silway link Silver to my DAC to NAD C-375 connection over my present Nordost Red Dawn.

My dealer friend disagrees with my approach that bi-amping will improve my sound as he said he conducted a similar setup with the PSB Synchrony Ones in his store and did not hear any differences. I am wondering if he is just wants to steer me in the direction of getting a Rogue Audio Preamp and NAD C-275 combination, which I have considered as well.

Any expertise and advice in this situation would be greatly appreciated. I unfortunately cannot tryout these situations or go listen to them in a store due to my location and have to rely on people’s advice.