Most solid state amplifiers produce extremely low distortion. But when the output level is too high for the supply voltage (clipping) then squarewaves with many odd-numbered harmonics are produced. Vacuum tubes can also produce clipping with squarewaves and odd-numbered harmonics but since their...
Maybe Bose feeds the speaker with a series impedance causing it to resonate and sound "boomy".
Maybe their little speakers have a peak at a mid-high frequency so they reduce the treble which makes the bass resonance too loud.
The small speakers in the long "waveguide" enclosure make a resonant "one-note-bass" that some people like to hear.
I like to feel and hear all the low bass notes.
Vacuum tubes produce even-harmonics distortion that some old people like to hear like they heard many years ago.
Even-harmonics are musical and are not harsh clipping distortion like an over-driven semiconductor amplifier.
Small speakers are probably fed through small coupling capacitors that also do do not produce low frequencies.
In a cheap clock radio, I needed to increase the capacitances of 3 coupling capacitors for it to produce excellent wideband sounds to an external much larger two-way speaker.
Today i received an email from Maker.Pro about making audio projects.
They seem to be from students in India.
The first one was a class-D audio amplifier with no audio specs.
The second was an LM386 audio amplifier IC with errors.
Both have videos showing a speaker missing an enclosure.
Why is this defective circuit from a student in India talked about AGAIN 8 years later?
This new copy of the original clear schematic is covered with a grid and has Multisim(?) jigs and jabs on many wires. It has additional errors like R3 is shorted and the base-emitter of Q7 is shorted.
Some cheap recorder systems are designed to record a voice. They cut frequencies above 3kHz like a 100 years old telephone did.
Then most of the talking was, "What? What did you say?" over and over.
I do not like the severe distortion produced by an electric guitar and its distortion pedals. The speakers used are far from hifi that I like.
An acoustic guitar recording that sounds the same as a live player is what I like to hear.
Your recording is missing high audio frequencies like an AM radio. Mayve the problem is caused by the very cheap mic or the "guitar speaker" or the bandwidth limited "voice" recorder app that produce no high audio frequencies.
You mentioned buying a cheapo electret mic on Amazon. It is modern and will probably work well.
Wkipedia says the 56 years old Shure SM58 dynamic mic is expensive so millions of poorly sounding fakes are sold (I think probably on ebay, AliExpress and Amazon).