The XLi noise spec is 100 dB A-weighted, and that’s the problem. An A-weighted spec rolls out the high and low frequencies (look up A-weighted response curve), which is typically where the noise is. What you want is an amp with an unweighted noise spec, also known as Z-weighted. An unweighted spec is 20 Hz – 20 kHz.
That said, an A-weighted spec can be adequate if it is unusually high, like 115-120 dB. But not something like 100 dB, as you already know.
There are at least three companies making an amplifier model A800, so can’t help you there.
The KM750 has a 100 dB unweighted spec, which should be good. However, Behringer has been known fudge their specs. If you get one, make sure it has a generous return policy.
Regards,
Wayne A. Pflughaupt