STV0910BD demod (TBS6905) have restricted support for VCM/Multistream DVB-S2/QPSK,8PSK. So can receive multistream 8PSK transponders with DTT muxes.
"Advanced" demod STV0910AD (TBS6983,6903,6908,5927) demod have full support ACM/VCM DVB-S2/QPSK,8PSK,16APSK,32APSK.