Yes, it's okay...but it's surprising to me.
A volume reading of 0db on a lot of receivers signifies some reference level (e.g. 70dB). So, the + and - readings are just offsets from that reference level. As you increase the volume, though, you'll be pushing the amp in that Yammy harder and harder.
I say that it's surpising because when I set mine to 0dB, it's loud. Quite loud. My speakers aren't vert efficient, either.