I have an old 1970s Pioneer Reciever that is in perfect shape and produces amazing sound. Since it doesn't have any digital inputs I purchased a digital to analog converter that runs from my PS3 through an optical digital cable then to R/W RCA to the reciever. When watching a movie through DTS MA HD the low bass ends are extremely crackly. I had it switched to Linear PCM output because I figured my reciever wouldn't be able to decode the DTS. But then I switched it to Bitstream (mix) and it worked. Low bass ends and all.
So am I getting the best out of my sound or no?
Looks like you are getting the best possible result. with that setup. All you'll ever get is stereo. Bitstream (mix) will be a high bitrate lossy encode. Excellent quality. You can try outputting stereo PCM from the dts-MA track, which might be slightly higher quality.