LoRez Recording and HiRez Playback

So, I'm pursuing a simple setup to allow me to listen to HiRes music from my computer. HiRes, to me, meaning 24/96. Which got me to thinking; Is there an industry standard for digital recording original music today? Can I assume it is at LEAST 24/96? What about something recorded digitally fifteen years ago? What about an analog recording from forty years ago?

When shopping for HiRes music, how will I know that I am taking full advantage of my playback system???
The last I heard, music is mastered at 24/96. Early digital had a few different mastering formats, but the end result was 16 bit/44.1 Hz for CDs (Redbook).
The problem with hirez download websites is that older music is still 16/44.1 even though they may be calling it Hi Rez. New music for sale would be actual HiRez 24/96 (if the seller is honest).
Examine the music file with a spectrogram app. If there is virtually no info above 22kHz, then at some point in the recording/mastering process it was reduced to a 44.1 recording.