I assume you wound up getting one AT853? Great mic but the mic itself can distort (unless you get the low sensitivity option) when taping in high sound pressure situations. Taping too near the speaker could cause that. Also if sound pressure was not extremely high, maybe the simple addition of a battery box would have handled that (most mics can tape record around 15 dB higher sound pressure levels with a battery box).
You really need to get a battery box (or preamp) and 2 mics whatever else you do. The battery box or pre will let you record a wider dynamic range and higher sound pressure levels without clipping. Very few recorders provided adequate power for most mics. The Church-Audio box costs only $30 is is barely larger than a 9 volt battery. Using 2 mics instead of one will add room ambiance and stereo crowd noise even if you are recording next to a mono speaker, which will make the recording sound much more natural and pleasing.
With a stereo pair of AT853's with the low sensitivity mod (or CA-11's or CA-14's), a battery box, and an H140 you should be able to make great sounding recordings of anything loud. For acoustic, you'd do even better substituting a preamp for the battery box. I love the Church Audio ST-9100 pre, as do many here.