I have no firsthand listening experience with the NAD C388. However, I do own a NAD C375BEE. Different from the 388 which is digital instead of analog. Without knowing the differences in these two amps this is what I have learned about my NAD experience......
After buying the 375 I tried it with some of the speakers I had as well as some at dealers' showrooms. Brands were Klipsch, KEF, Focal, Dynaudio, and some others. When paired with the NAD amp none could compete with PSB speakers. NAD and PSB were once sister companies. Again...I'm comparing bookshelf models.
Now, I use my NAD with a pair of PSB Imagine B's. I like the sound. I also use a pair of subs since my room is on the large size but without the subs the sound is still good. If looking at PSB bookshelves the only step up would be a pair of Synchrony 1B's. I would like to find a nice pair of those just to see how much better they sound compared to the Imagines. Just my opinion. Trust your ears.
After buying the 375 I tried it with some of the speakers I had as well as some at dealers' showrooms. Brands were Klipsch, KEF, Focal, Dynaudio, and some others. When paired with the NAD amp none could compete with PSB speakers. NAD and PSB were once sister companies. Again...I'm comparing bookshelf models.
Now, I use my NAD with a pair of PSB Imagine B's. I like the sound. I also use a pair of subs since my room is on the large size but without the subs the sound is still good. If looking at PSB bookshelves the only step up would be a pair of Synchrony 1B's. I would like to find a nice pair of those just to see how much better they sound compared to the Imagines. Just my opinion. Trust your ears.