I finally managed to decode some of the MFSK from the Shortwave Radiogram program at 1500 UT today, though it was tricky, as even with an at times 19.0db SNR, the constant drop outs that even the slightest fade cause on a 5 kHz bandwidth are enough to knock the signal out for long enough to miss the RXID codes, so you have to be manually changing the modes at times.
Still, my system of decoding DRM on one sound card and feeding it into the other card for the Fldigi decoder is at least working well, and when the signal is there there it decodes very well, and even the bits in Persian came across okay this time.
Modified NRD-525G with Radiokit DRM Decoder Board,
SDRplay RSP-1A, Airspy HF+ Discovery, Dream v2.1.1
Lancashire, UK 53:39.18N 02:10.28W IO83vp