Hi,
The master volume on your RXV1300 also increases the line-level signal to your subwoofer when you turn up the volume, so the relative sub level will match that of your fronts and surrounds. But our ears vary dramatically to deep bass sensitivity depending on the SPL level. Deep bass has to be many times louder than midrange and highs, especially at low overall volume levels, so you may want to tweak the sub level separately.
Our hearing sensitivity to deep bass was first investigated and measured by two researchers, Fletcher and Munson. The old "Loudness" control found on many older Yamaha preamps and receivers attempted to automatically compensate for our deep bass insensitivity at quiet listening levels. It gradually boosted deep bass according to the Fletcher-Munson curves as you turned the "Loudness" control down (it was separate from the main volume control).
Regards,
