To DAC or not to DAC

I just purchased a relly nice Theta Miles CD Player to replace a Marantz 6000 OSE with a MSB Link DAC w/ Upsample chip. I love the Theta and the clarity and depth are much improved, not to mention the incredible build quality.

However, I wonder if it would make sense to use the MSB DAC with the Miles? I know the internal DAC in the Theta is great, but I wonder if it would improve or ruin the sound by incorporating the MSB DAC. If I understand correctly, by using the digital out on the Theta, I would be by-passing the excellent onboard DAC in the this correct? If this is correct, I'm not real excited to turn this excellent player into a simple transport.

Please let me know what your thoughts are on this matter.

By the way the Miles unit is the balanced version.

Thanks for your input.
Perhaps I don't understand your question, but why don't you try it both ways (with the DAC hooked up to the digital out on the Theta vs using the analog out from the Theta) and see which you like better.

Using the MSB with the Miles does by-pass its internal DAC.
Sidssp is correct. I agree with Michael, you could borrow a digital cable from a friend and compare them both, see which one sounds better to you. Very easy to do and completely reversible. I would be surprised if the difference between the Theta and the Marantz as transports would be as much as the Theta's analog stage vs. the MSB, but you never know in this hobby...
Agree with all above. I think your questions are fully answered.

Well, I did an A-B comparison......and there is no comparison!!!

The MSB is absolutely NO MATCH for the incredible Theta machine. Adding the MSB Link DAC was like putting a VW motor in a Porsche Turbo body. MSB is in a totally different class.

I have to say I'm relived that my money was well spent on the Theta Miles.
Perhaps yes, perhaps no. You see when you separate transport and dac you introduce "jitter". You also introduce a number of other issues, like; power cords, additional shelving, proper isolation, cabling. Any one of these can take an otherwise great upgrade and render it blah. If you got a good Miles (apparently there are unit to unit sonic differences), look at upgrading elsewhere first, as you've done well.