Yay or Nay

If you enjoy what you have, I'd say Nay.

The CAmbridge would sound different I am sure but not necessarily better.

I tube DAC like mhdt Paradisea might be a more interesting alternative in that price range. You can roll different tubes with that unit to change the sound significantly for marginal cost as well if you like.

At best, a lateral move...most likely different, but not better.

The creds on the Apollo speak for themselves - stand pat.

Having used both the Apollo and Cambridge Audio Azur 840C extensively, I can say that the sound between them is rather different.

Big assumption: The DagMagic would be along the lines of the Azur's sound. It is very likely you would see an improvement. However, I agree with Mapman that a tube DAC would further distance you from the Apollo's sound (Likely in a very positive way).

Finally, do not skimp on the Digital cable for the DAC as it has a strong influence on the quality of the resultant sound.

I have used the Monarchy M-24 pre/DAC with several players acting as transports. I used the Rega Saturn with the Monarchy and it was superb, a very rich upgrade in warmth and nice expansion of sound stage from the Saturn alone.

So, I would think that the similar transport of the Apollo would similarly be vastly improved by a good outboard tube DAC.

Oh, forgot; Disclaimer - I reviewed the Saturn, Azur and M-24 for Dagogo.com