Mmm. Browsing the product web page, it says that mic gain range is -15dB to +65dB.
PreSonus | AudioBox 22VSL - Techspecs
It does indeed say that...
Mic Preamp EIN -129 dB, 20 kHz BW, max gain, Rs=40Ω, A-wtd
Frequency Response 20 Hz - 20 kHz, ±0.3 dB, unity gain
THD+N 0.005%, 0 dBu, 1 kHz, unity gain, 20 kHz BW, A-wtd
S/N Ratio 94 dB, 0 dBu, 1 kHz, unity gain, 20 kHz BW, unwtd
Gain Control Range -15 dB to +65 dB<<<<<
Input Max Headroom +10 dBu, < 0.5% THD
Input Impedance 1.7 kΩ
Phantom Power +48 VDC, 10 mA total
But that is a near electronics impossibility IMO. To get a gain range of just 0dB to 55dB inevitably means some "cramping" of the gain at higher levels and many budget mixers and AIs are notorius for this (
my Fast Track pro is one such). To get a range of 80dB is unheard of and would make the last 20dB or so practically unusable in my view (but maybe they have a "boost" in software?).
But back to the OP's problem. I now suspect he is not playing loudly enough! Most guitar amps have a very poor "self noise" (PM me if you want to know of one that is positively high fideliteee, in this respect!) so you need to have the amp kicking some 90dBSPL into the room to overcome the background noise. This of course is not always possible for social reasons and so the other recourse is to a speaker attenuator or Power Soak as I prefer to call them. For amps up to 15watts or so they are beer into water to make and cost less than $50.
Batgol: Mixer! Sorry, missed that. Yes, you could use a mixer with
the audiobox. The mixer outs would feed the combi line inputs but I am not sure it would help you with your current problem. see above.
JUSFORT! Have you tried singing into the mic well away from the amplifier? If that is clean (you need a mic to gob distance of about 8inches) it is the amp or guitar/amp system that is causing the noise.
Dave.