Yamaha 150 Owner's Manual page 7

You can also connect multiple speakers with a different rated input to a single channel. For example, you can connect
ten speakers with a rated input of 5 W and ten speakers with a rated input of 10 W (total 150 W), as shown below:
CHANNEL B
Note: Be sure to use speakers that support the XH150's line-out voltage (70 V or 100 V).
Note: You cannot connect a low-impedance speaker directly to the XH150. In this case, be sure to use a
speaker transformer (such as the Yamaha ST15). Follow the instruction guide that came with the speaker
transformer to avoid excessive loads.
SPEAKERS
CHANNEL A
+ +
– –
70V = 32 /CHANNEL
100V = 64 /CHANNEL
Rated input
5 W
5 W x 10 units (= 50 W)
5 W 5 W 10 W
10 W x 10 units (= 100 W)
50 W + 100 W= 150 W
10 W 10 W
7