Hi there, i'll chip in with what i make of the lead advertised.
From ad-
This adapter allows an aftermarket head unit to be installed, whilst maintaining the factory fitted amplified system. This adapter is designed to match the correct impedance of the vehicles speaker system.
This tells me that the lexus amp will still be in use (thats how i read that sentence anyway)
From ad (the enlarged attached pic)-
2. Remove the larger of the 2 plugs from amplifier
3. Plug this lead into the adapter
This is by-passing the amp, plugging the LEAD into the ADAPTER, maybe i'm reading the ad wrong, or it is not very well written, but to me it looks like this is a "amp by-pass cable" just made by connects2 and not autoleads.
Either way, sure you will let us know when you receive it, and let us know how it sounds.
PS, its the best thing you will ever do is change that stereo, still love mine & it's been in over a year now.