Ok, I went back in and did some dithering about with the software side and here's what I found:

First, if I change the Akai's inputs from "Line" input to the one used for "Guitar" and other high-impedence inputs, the volume drop relative to the Yamaha card I had been using drops. I must have had it set differently before and changed it when I was testing a Roland synth box via the same inputs. Again, my mistake.

At the same time, I do notice that the output IS still lower than that of the Yamaha, just not as dramatically as I'd originally thought. I don't need to max the Akai out, but I have far better results using the speaker output of the SB16 (keep in mind, the Akai is also my primary "sound card" on my main machine, so the last thing I need is to get an email and wet myself from the deafening noise that'd result from having this thing cranked to run DOS).

I did check SB16MIXER and found that all of the levels were pretty maxed out, which wasn't surprising as I assumed that to be the default.

With regard to my config files, CONFIG.SYS has nothing SB related in it. AUTOEXEC.BAT has the following:

SET BLASTER=A220 I5 D1 H5 P330 T6
SET SOUND=C:\SB16
C:\SB16\SBCONFIG.EXE /S
C:\SB16SB16SET /M:220 /VOC:220 /CD:220 /MIDI:220 /LINE:220 /TREBLE:0

I'm not sure if that tells anyone here anything that it doesn't tell me, but that's the best info "on the ground" that I can give unless there's something else I should be looking at as well. I probably won't get a chance to pop the card and check jumper configuration until tomorrow, but that will be the next logical step, I suppose.

Thanks, as always, for the info and input so far.