cdp+outboard dac

when a cdp is used as a transport does the basic sound of the cdp effect the sound coming from the outboard dac?
From what I know, it does. I use a Pioneer CDP exclusively as a transport, hooked up to a Bel Canto DAC. Modwright took the CDP and modded the heck out of it for use strictly as a transport.
Yes, although if by "basic sound" you mean whether the same machine's sound *as a CD player* can be considered determinative, then I'm not sure how much correlation there is in that sense. But just in general, transports -- including players used as transports -- absolutely affect the overall sonic output of the DAC they're paired with. Personally I've never obtained as a good a result using a mass-market or mid-fi player as a transport vs. using a high-end dedicated transport, though I haven't tried the modding route. BTW, I've also found that using an anti-jitter box in-between doesn't narrow the performance gap.
There are a lot of reasons for transport/cdp to effect the sound of external DAC.
The main one is the jitter on SPDIF or AES/EBU output (digital outputs). Usually the more expensive transports have less jitter, therefore they sound better, however the external DAC's could deal with jitter too, we have just finished design
and built a prototype of such a DAC.
The results are stunning!!!
In our listening sessions we could not detect any sound differences between CAL Delta transport($500 used) and top of the MBL ($11,000.00 used). Whats more amazing, cheap ($99) Sony DVD player sounded as good as PS Audio ($2000) transport.
The other issues with different transports /cdp's that effect the sound are related to the error correction and interpolation techniques, no external or internal DAC coud correct for those.
Hope it helps
3Dimension Audio