The NAD formula was high value and good quality with modular design. Need it to be a pre-amp only? - just pull the jumpers on the rear panel. Same thing if you want it to be a power amp only, or any combination when bi-amping. The 3020 and it’s related models (integrated amps, receivers, amps, preamps and tuners) and descendants are all part of this architecture mindset. They didn’t believe in reinventing the wheel in those days.
NAD today is on an entirely different path - digital digital digital. Not for me.
To the OP, if you can get a 3020i in good condition for C$250, you are doing well. They are well worth it.