The S5.5 won't work well for the NS5000. I spoke with Doug Dale @ CODA about this amp and the NS5000. In fact, I use a CODA #16 on the NS5000 right now. It is a terrific pairing. The S5.5 will work on the NS5000, just like a stereo AHB2 would work. However, this speaker sounds better to me with more power than the S5.5 can deliver.
I am only looking to add another amp because the amp I use in another system would sound better if it was replaced with one of the following 3 amps, SimAudio North | CODA #16 | Luxman M10X.
I would rotate 2 amps with 2 systems. Currently, I cannot do this because my current second amp does not sound great on the NS5000.
Doug said that the new (or updated) CODA System S150 + SV would be his top gear.
CODA S150/S250 Amplifier System – Destination HiFi ($20k)
CODA SV System Voltage Amplifier – Destination HiFi ($8k)
This comes a little under $30k. Since I already have the #16, I decided not to look into the S150.