I just pruchased a used D150A and downloaded the service manual from this site, but I'm a little confused. Is it safe to run the D150A at 4ohms per side? I've got four 8 ohm 10" speakers rated at 120watts each, and I'm going to run two of them per side with the D150A in mono mode. If I configue a pair of these speakers in series, they will be 16 ohms and the amp will run them at about 65watts per side. I've also seen a rating of 90watts at 4ohms in the service manual but it doesn't seem to recommend this set up, and I'm not clear if it means 8 ohms per side or 4 ohms per side.
If I configure a pair of 8 ohm speakers in parallel they will be 4 ohms, can I safely run two 4 ohm loads on the outputs of the D150A in mono mode? I'd like to run this configuation if possible in order to gain the additional power from the amp, but I'm not clear that the D150A is rated to run that way.