You will get improvements either way by upgrading your CD player or the speakers. I guess you question lies in which upgrade will yield a bigger difference in sound improvement.
I have owned the B&W N805 and still have the CDM1SE's for my rears in HT duties. The CDM1SE's are good speakers on their own and you will definitely hear a difference in upgrading your source, but they have their limitations. As good as the CDM1SE's may be, the resolution and detail retrieval of the N805 will be a significant improvement over the CDM1SE. In comparison, the midrange is fuller and more open, highs more refined and bass goes considerably lower and more controlled. Overall the N805 is a nice step up over the CDM1SE. The 805S is a better speaker than the N805 so you can expect even greater improvements.
Having said that, you wouldn't obtain the full potential of the 805S should you decide to upgrade the speakers first. You can upgrade the CD player first, then the speakers. OR, you can upgrade the speakers first, then the CD player. Either way you get improvements. Personally if I were you, I would upgrade the speakers first, save some money and upgrade the source a few months down the road.
I have owned the B&W N805 and still have the CDM1SE's for my rears in HT duties. The CDM1SE's are good speakers on their own and you will definitely hear a difference in upgrading your source, but they have their limitations. As good as the CDM1SE's may be, the resolution and detail retrieval of the N805 will be a significant improvement over the CDM1SE. In comparison, the midrange is fuller and more open, highs more refined and bass goes considerably lower and more controlled. Overall the N805 is a nice step up over the CDM1SE. The 805S is a better speaker than the N805 so you can expect even greater improvements.
Having said that, you wouldn't obtain the full potential of the 805S should you decide to upgrade the speakers first. You can upgrade the CD player first, then the speakers. OR, you can upgrade the speakers first, then the CD player. Either way you get improvements. Personally if I were you, I would upgrade the speakers first, save some money and upgrade the source a few months down the road.