I am a big fan of multichannel, both DVDA and SACD. I do not use the stereo tracks of my discs, but it stands to reason that these would be better than a CD (except that how the particular disc was recorded can make or break either format). However, I think that an effective multichannel system requires center and surround channel amps and speakers that are equal to the left and right, prefereably the same. This can be expensive.
I think that a universal player makes sense. Then you can buy any disc that strikes your fancy without worrying about whether you can play it. I would be leery about dual discs because they are slightly thicker and do not play in all players. In recent years technology of D/A converters has advanced greatly, so even an inexpensive player will sound quite good in your system. The differences in players relate to what they do with the analog signal after the D/A conversion. These circuits serve all the formats, CD, SACD, DVDA so all can be expected to improve with a more expensive player.
I think that a universal player makes sense. Then you can buy any disc that strikes your fancy without worrying about whether you can play it. I would be leery about dual discs because they are slightly thicker and do not play in all players. In recent years technology of D/A converters has advanced greatly, so even an inexpensive player will sound quite good in your system. The differences in players relate to what they do with the analog signal after the D/A conversion. These circuits serve all the formats, CD, SACD, DVDA so all can be expected to improve with a more expensive player.