rattler,
If your recordings are playing back with low volume, I'd suggest that you check your Master Compressor settings.
I've found that the "Output" setting controls the recording level on my SX-900.
I use Reaper as my DAW, but any DAW has the ability to show you your record levels. In my case, with my Output set to 90, I get average RMS readings of -18db, with Peak levels that are just under 0db. No distortion, and they are obviously recorded at the proper level.
If I set my Output to 45, for example, it is now recorded very obviously too low. Both MIDI and Audio recordings act this way. Your "Compression" setting will also affect the apparent loudness, and you'll just have to experiment with the settings to your taste, but I suspect this is why your recordings sound quiet. Hope it helps! Jerry