Audio Electronics

I have this old pair of Technics SB-3130, they are three way speakers. Both of the super tweeters are dead (infinite resistance) and I'm not sure if this impact the range of frequency feeded to the tweeter. Given the schematic diagram, if I remove the super tweeter, should I modify something to have all the high frequencied to the tweeter?

I have an old Bose SoundLink Mini II Bluetooth speaker that sounds quite decent to me. I want to upgrade/replace its internals with a Raspberry Pi Zero W and an audio DAC Shim attached to it, running piCorePlayer.

Since the Audio DAC Shim doesn't provide enough power, and the Bose seems to have a separate amp board, I want to use the amp board of the Bose to drive the speakers and eliminate the rest of the Bose PCBs. The amp board controller appears to be a TPA3118. With the help of the datasheet, I found out the audio input pins of the board:

LINN (Left IN negative) LINP (Left IN positive) RINN (right IN negative) RINP (right IN positive)

The RPI Audio DAC Shim only has a 3.5mm headphone out, so Left, Right, and GND.

I already tried to connect it as follows:

L to LINP R to RINP GND to RINN and LINN

While this seems to work in general, the audio quality appears to be worse in comparison. When I plug the RPI DAC Shim board into the original Bose 3.5mm input (using a 3.5mm cable), it sounds better.

Here is my question: Is it fine to connect the 3.5mm signals as I did? It felt wrong to just connect RINN and LINN to GND, as RINN and LINN don't seem to be connected to GND otherwise. How do I properly connect the 3.5mm output to the Bose amp board?

Cheers

I am trying to use a lav mic with my headphones cause the inline mic for them broke. The headphones only have a TRRS output and the mic has a TRRS with a TRS converter/adapter. Can I find a 2 female TRRS and TRS to 1 male TRRS 3.5mm adapter? Would a 2 TRS female to 1 TRRS male adapter work in this scenario even tho my headphones are TRRS only? I know the mic sleeve is the end ring so maybe I dont need to fully plug in the headphones cause I'm trying to use another mic anyway.

These are the three things I have found -

Lav mic - https://www.amazon.in/Maono-AU-400-Lavalier-Microphone-Black/dp/B07JF9B592

Splitter(jack type unknown. possible 2 female TRS to 1 male TRRS) - https://www.amazon.in/Kinsound-Male-Female-Smartphone-Laptop%EF%BC%88Grey%EF%BC%89/dp/B089NVPFYY

Splitter(apparently 2 female TRRS to 1 male TRRS. practically perfect for my purpose) - https://www.amazon.in/CABLESETC-Universal-Microphone-Duplicator-Splitter/dp/B01MXPFQ85

I am not an avid electrical engineering guy. Just trying to fix some stuff with the limited knowledge I have.

Some pictures and a schematic that I traced out during the repair of an Audio Technica AT803b preamp