Mixing battery chemistries

I have a set of ear protection muffs with am/fm that took 2xAA batteries that I use at work.
I hacked in a Bluetooth and switched to a lipo battery, 1350mah I think. Worked pretty good, something like 9 hours of Bluetooth.
Well now I'm on 12 hour shifts so I needed an upgrade.... So I added 2x 800mah 14500s

I know mixing chemistries is not advisable, but at such small capacities and it being monitored at all times during usage, I figured what the heck.

So what kind of danger am I putting on my head everyday?

You are probably gonna be fine, because you aren't fully charging the cells, or fully discharging.

2xAA: 3V Nom, 2.4V - 3.6V range
This is fine for the Lipo

The 14500's will be operating in under-voltage conditions. You're basically going to shorten the life the 14500s. They can run at higher voltages than the Lipo, but you aren't doing this, so mixing them is fine. But also, you aren't running them at their "proper" voltages either, so they won't last long. Well, long could be 500 cycles perhaps, or maybe more. That would be almost 2 years of use if recharged every day.

I agree with Korishan. But both will be operating undervoltage if the Lipo cell isn't a Lifepo4 cell
https://en.wikipedia.org/wiki/Lithium_polymer_battery
The voltage of a LiPo cell depends on its chemistry and varies from about 2.7-3.0 V (discharged) to about 4.2 V (fully charged), for cells based on lithium-metal-oxides (such as LiCoO2), and around 1.8-2.0 V (discharged) to 3.6-3.8 V (charged) for those based on lithium-iron-phosphate (LiFePO4).
later Floyd

I'm unsure of the chemistry. It's a 3.7v foil pouch (prismatic?) cell, and I'm just assuming it's different from the 14500.

But I was using the charger specifically from that lipo. So they are getting it's full charge, which I thought was 4.2v. I've recently just been using the Bluetooth headphones built in charging port.

Discharging fully with Bluetooth shouldn't run them low, as it originally used a 3.7v 60mah foil cell.
Discharging fully with am/fm I was unsure about, but if 2xAAs are 2.4-3.6v it looks like I'm safe there too.

As you might be able to see by the condition of my prolly 6 months of use battery, I'm not too worried about the shortened lifespan... If they die I might just load it up with 18650s and get a full weeks worth of charge

3.7v would be approximately the same nominal voltage as the 14500's.
The ear muffs seem to handle the extra .6 volts for at least 6 months. sounds good.
later floyd