Primary impedance=2 kΩ.
The transformer designer will immediately want to know the secondary load impedance, and because loudspeakers are not pure 8 Ω resistances, it is usually better to design for a 4-Ω load. Since a good output transformer has multiple secondary sections, transformer manufacturers commonly offer four sections that can be configured for 1 Ω, 4 Ω (preferred setting for practical loudspeakers), 8 Ω and 16 Ω (ideal if you could find a genuine 16-Ω loudspeaker).
The next important question is the lowest frequency for which maximum power is required. This is an expensive question. As an example of classic commercial practice, the Leak Stereo 20 and TL12+ amplifiers could only produce their ...