Musical Fidelity A1 I

I do not have a turntable and listen mostly to SACDs and CDs (some BD Audio). Do SACDs get read by a dac? If so, my OPPO 105 has a built in SABRE dac. The M3si has a dac and phone stage, but not the M2si. Same power output for both. I read that the SABRR dac in the 105 is easily improved upon with a quality external dac. I don't know if the M3si dac is any better than the Oppo. Am I getting inferior audio quality due to the quality of the OPPO dac since I listen to mostly SACD? (I am pretty confused as a beginning audio enthusiast😁). It sounds like the OPPO main strength may be its video quality? Right now, I have my system wired this way: Standard speaker wire from speakers to speaker terminals on Onkyo TX-SR706, and standard RCA cables from Onkyo preouts to AUDIO OUT on OPPO. That's it. Are those optimal connections for best sound? I may be limiting performance with wrong  connections? Better wires and interconnects were suggested, but I have read that would make little difference. I just assumed the Triangle's were bright and the amp was bright (not a good pairing). It isn't unbearable but harsh up top and probably lacks detail retrievable and dynamics that a better amp would provide. I AM impressed with the detail retrieval and midrange from them. The Onkyo is rated at 100 watts per channel, but I question how efficient those watts are verses a stereo amp. Questions, questions! I want to do this right the first time. And listen to the music I have so painstakingly acquired the last few years. I am practical and budget minded, yet I am willing to splurge for quality audio. Speakers are $2000 ($600 used like new, love the simplistic box design), Oppo 105 was $1000 used like new --- purchased last year, and the Onkyo was $400 used I think. So I have $2000 in it. I can see buying a good amp (maybe better dac?) if it will increase performance. And an amp should vs the Onkyo SS receiver. Thank you!!!! Looking forward to more sound advice on the amp model and my current connections, and clarification on SACDs going through a dac and the possible need for better dac to get the best sound. Now that I think about it...my Bluray movies sound more full and rich compared to my SACDs! Maybe it is the dac.

I have run my M3si with Triangles using Kimber PBJ and AQ Type 4 wires. I can recommend that. I also own the Onkyo integrated at 100wpc. The M3si is a much better amp. 
The Triangles have an extended top end and will sound best with quality recordings but they are also very satisfying with lessor quality recordings. 

Thanks Russ. The M2si is $1000 new vs M3si at $1500. Same watt amp minus the phono and dac. What advantage is there with the M3si? Would the dac better than the Oppo Sabre dac? Much appreciated! BTW what Triangle speakers do you have?

Good for you second guessing that particular used amp. It sounds like it’s had a hard life!  

Yes, there are a lot of uncertainties with a 35 yr unit. Ok my new thread in the amp section, russ69 has shared that he owns Triangle's. I feel his recommendations are sound. Just not sure if I need a better dac than my Oppo Sabre dac, to get better sound from my SACDs. Want to do it right the first time if I can.