Alan Parsons Project's Eye in the Sky is an excellent album (especially when decoded with a lossless codec).
The Blu-ray has these soundtracks:
Music: DTS-HD Master Audio 5.1 (96kHz, 24-bit)
Music: LPCM 5.1 (96kHz, 24-bit)
Music: LPCM 2.0 (192kHz, 24-bit)
According to the
Rotel RSP 1068 Manual the Decodable Digital Input Signals are Dolby Digital, Dolby Digital EX, DTS, DTS-ES, DTS 96/24, LPCM (up to 192K), HDCD, MP3, MPEG Multichannel
You are correct, the best you can get is DTS 5.1 which the Rotel 1068 AVR will auto detect the signal and play it when you select it on your Blu-ray player.
I'd encourage you to look to upgrade to something that has a good Sub and will play lossless source material.
I hope this is helpful.