Congrats on the TLX. The A-Spec is a sweet looking car. It's a shame that it does not have some of the stuff in the Advance package. Acura constantly shoots itself in the foot by doing things like this, or not having some of the features in the lower priced Honda similar models. I could never understand that.
I had a 2018 loaner TLX (not A-Spec) but with DTS and I have to admit it does sound better than the DTS in my 17 RDX, but there are some discs that I have that actually do sound good in my car, despite my initial howling about it. I can't put my finger on it, and it's not EQ, because I've tried many things. I am sure that the DTS stereo enhancement is nowhere near as good as the Dolby in the earlier DVD-A systems, I swear a lot of my regular CDs sound mono in the car.
There is a big unveiling on Monday (Jan 15) at the Chicago Auto Show of the 2019 RDX which is supposed to be completely re-engineered. I can not find anything out about it yet, but it sure would be nice if it did USB .flac. I am not even sure if it will even have a disc player, but we'll see.
In the mean time, that A-Spec is one styling machine, and I wish you the best of luck and enjoyment with it. Having the DTS is far better than fake surround, that's for sure.