Not ML audio just standard. I did upgrade my speakers which made a huge difference very glad I did that.

 

Streaming music or ripping your CDs to a tiny, large capacity USB stick are your best options, IMO. Another option, I prefer not to pay for streaming data, so I store about 800 carefully selecting tracks on my phone.

 

I would not touch your new infotainment system in a hurry.
Lexus will blame you if it fails for any reason if you have made mods to it during warranty and will refuse to cover it.
You will then end up paying for a new system.
You can however buy an external CD player which has a bluetooth output.
Then the problem will be you won't be able to connect your phone and the CD player at the same time...
So you will need a second "bluetooth" input into the car.
You could try Raspberry PI running BlueALSA + USB Audio Gadget (UAC). Bluetooth in → USB audio out to the car..
So the car will think it is a USB memory stick that is plugged in and that it is just playing a file..